Servicing small refrigeration units




1. Servicing Equipment and warning about tampering with refrigerant BD50 SCM

2. Servicing Capillary Tube

3. Checking Refrigerant Charge Systems

4. Climate temperature variations will change refrigerant volume Why?

5. Adding 134a with Stop Leak

6. No Refrigeration servicing port fitting

7. AB and other Danfoss BD compressor system servicing

8. Danfoss refrigerant charge Servicing

9. Refrigerant Charge and pressure.

10. New Isotherm Pre-Servicing Leak Testing

11. Different ways to service Small 12/24 Volt Refrigeration

12. Servicing a Frigoboat System.

13. Cool Blue Refrigerant Servicing with an Expansion Valve

14. Vacuum Pumps Servicing

15. Another vote for Do It Yourself Servicing

16. Standard Danfoss BD Compressor system adding refrigerant and leak testing


17. Servicing Danfoss BD System after replacing evaporator

18. Frigoboat BD leaks and servicing

19. Add refrigerant to AB


20. Servicing small 12 volt units by frost level with correct Refrigerant

21. Refrigerant. Charge AB Adler Barbour Forum archives


1. Servicing Equipment and warning about tampering with refrigerant.BD50 SCM-

I have an AB Super Cold Machine system on my trawler. It has been running since 2000 and is taking longer to cool. The minimum freezer temp used to get down to -4˚ at the bottom of the cycle and now it doesn't get below 0. I think it needs a little charge. When I take the cap off the service fitting on the BD50, I don't recognize the fitting. Can you tell me what exactly is that fitting and what do I need to mate with it for my gauges? Also, where can I get an adapter? I have just ordered your book "12-24 volt refrigeration". Does it contain the procedures/pressures, etc for recharging the Super Coldmachine or, if not, do you know where I can get them?

I used to maintain my old R-12 system, but when it gave up the ghost, I installed this Adler Barbour system (r-134a) and have been pleased with it. However, fittings, etc are different on this one and I am not sure just how to proceed.

Answer:I don’t like to connect gauges to a system until I have proven that the refrigerant is the problem. Are you sure there is adequate airflow through the condenser? If your evaporator is a thin aluminum plate and not an Adler Barbour Power Plate the frost line will indicate if the refrigerant charge is correct. When there is sufficient refrigerant there will be frost covering 95% of the evaporator’s surface and no bare spots. One half an ounce too much refrigerant on a small cap tube system could double the daily amp-hrs consumed, see chart on page 56 in the book you ordered.

You will find answers to your questions on connecting 134a refrigerant to your present gauge set on page 57 under Preservicing Information. Rather than buying both the Servicing adapter and the Female Disconnect, pictured on page 57, I would use the pieces you already have. From your description someone has installed the Acme Fitting also pictured page 57 on compressor suction service port. Adler Barbour’s new super cold machine with BD 50 compressor has the same components as the cold machine except the super unit has a small supplemental water condenser on a liquid pressure line. Servicing a DB50 with a capillary tube expansion device is the same as servicing your old BD compressor except with 134a there is a small pressure difference. If you do need to add refrigerant follow the steps listed on page 58 and 59 to the letter and you will end up with an efficient system.

From information you provided I feel that tampering with refrigerant will be a mistake as it sounds like a change in conditions not refrigerant volume.

Things to remember if refrigerant level is in question:
• Do not connect gauges needlessly and always perform non destructive testing first.
• Purge gauge set.
• The box and complete system must be warm when adjusting refrigerant charge.
• Adjusting refrigerant charge when evaporator is cold may not produce good efficiency.
• Don’t connect refrigerant gauges when compressor is running, as it is a good way to contaminate refrigerant.
• The servicing sealing cap must have a good seal inside as many leaks occur here.

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2. Servicing Capillary Tube Systems

What is the proper refrigerant pressure on the above remote marine refrigeration unit? Further, does the acceptable refrigerant PSI vary when the compressor is running vs. when the compressor is stopped?

Answer:Capillary tube refrigerators are designed to be serviced by volume in weight and not pressure. When the refrigerant volume is correct there will be frost covering 95% of a standard evaporator and none on the return line outside of refrigerator. It is a mistake to connect pressure gauges to a system unless you are positive compressor is running and frost coverage is not as it should be.

Suction pressure on a static system has no relative meaning except to say there is some pressure in the system. After a warm system is first started with ambient temperature of 70 to 80˚, suction pressure for Freon R12 will stabilize in a time window of 10 to 20 minutes at a pressure of 8 to 10 psi. For 134a refrigerant, pressure will be 6 to 8 psi. After 20 minutes pressure will decrease slowly as evaporator temperatures drops. At zero psi evaporator gas temperature could be -22˚. If you look at the face of a low pressure refrigerant gauge you will see each refrigerant’s pressure to temperature relationship.

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3. Checking Refrigerant Charge
It is very easy to tell when a refrigerator with a standard evaporator has the correct charge of refrigerant by the total area of frost on the evaporator. If 95% of the evaporator has frost on it, the refrigerant charge is adequate. As refrigerant is lost, the frost will disappear on part of the evaporator. An overcharge of refrigerant will result in frost outside the box on the line returning to the compressor.
Frost line method for determining refrigerant charge cannot be used on holding plate or Po

 4. Climate temperature variations will change refrigerant volume Why?

I have an EZ Kold with DB50 compressor. I set the suction press to 10lbs at an ambient temp of about 85˚ last spring when I installed the unit. It would run about 20 min out of every 80 min in the summer. Now that the ambient temp is in the 60's, it runs for up to and sometimes over an hour out of every approx three hours. Still about the same duty cycle ratio, but why are the running times longer when it is colder outside? I do not know the pressures in the system now as I borrowed the gauges to set up the system.

Answer: I can offer a couple possible reasons why the compressor runs longer now. On a capillary tube system with a 25˚ drop in condenser cooling from when it was originally serviced, the pressures both high and low will be low. This means the compressor runs longer because refrigerant flow is less but in most cases still consumes less daily energy. To increase the refrigerant volume now will cause poor performance in warm weather.

If your EZ Kold unit has the automatic speed up feature and the battery voltage is below 12.5 volts and was originally serviced with normal 12.7 volt battery voltage, maybe the battery is not fully charged allowing compressor speed to drop to minimum speed.

Reply: The unit is preset at high speed and the batts are constantly on a charger so voltage is constant. I suspected exactly what you said about the pressures now being lower in lower ambient temp and therefore taking more time to remove the heat. I had just never run across this situation before and wasn't sure if it was normal. Yes, I agree that adding refrigerant now would upset the operation in hot weather. That is why I originally set the pressures on a hot day.

Answer:In the last few years I have see the reverse problem to yours on new pre-charged systems when boats head south into tropical waters. Manufacturers of 12volt capillary tube systems offer more than one evaporator for their systems but do not always adjust the pre-charge of refrigerant accordingly. The problem shows up as high daily power consumption and reports of frost on return line to compressor due to a refrigerant overcharge. There is still a possibility your system is slightly low on refrigerant but I would not connect gauges to it at this time. Wait for warm weather. A little low on refrigerant is much better energy wise than a little too much refrigerant.

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5. Adding 134a with Stop Leak

Is it ok to use refrigerant with stop leak included? I am in a remote location if Africa and I can't get pure refrigerant without stop leak in it.

Answer:Stop leak mixed in refrigerant reacts with air and moisture in the air (humidity) to form a solid, polysiloxane (epoxy) seal at site of a leak. Leak Stop also incorporates an active ingredient that rejuvenates the seals, gaskets and O-rings in the A/C system.

I would not recommend adding refrigerant from a stop leak can, as it might add additional oil or sealant, either one of these may permanently block refrigerant capillary tube. There are two types of refrigerant stop leak solutions one has an active ingredient that rejuvenates the seals, gaskets and O-rings and the other reacts with air and moisture to form a solid epoxy. Any solvent that softens seals may affect compressor motor winding insulation.

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6. No Refrigeration servicing port fitting

What is the best way to add refrigerant on this unit not having a service port? My thought was to buy another resealing coupling and solder on a short length of tubing with a valve on the other end or some type of piercing valve on the appropriate section of tubing. I would think that should be done on the low pressure side. This unit has never been hooked up to the evaporator and as there are no instructions, is there anything I need to know about before testing it out. Do I just hook up the couplings, thermostat, and 12 volt power? I thought I might need some type of insulating panel incorporating a spill over damper. When installing the evaporator is it best to have a tight fit or to have some airspace around the sides and bottom? Are these types of problems and questions covered in your book? Thanks for your help.

Answer: If the metal sealing caps are still on the two units there is a chance that the refrigerant charge is OK. Adler Barbour did sell a gauge with additional quick disconnects to be installed at the suction line connector.

A servicing fitting can be bought with a short ¼ inch line attached that can be installed in the process fitting on top of the compressor or in the copper suction line with a solder T .A self piercing clamp on refrigeration service port could be used in an emergency but, I don’t recommend them as they may leak.

My 12 volt book does not deal with box dividers or spillovers. If you send me the inside box dimensions I will send a design for a spill over system for that box.

Yes I do think you need my 12/24 Volt Refrigeration Manual.

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7. AB and other Danfoss BD compressor system servicing

Question My Adler Barbour unit appears to work but does not get cold. The fan runs and the unit runs. I have a set of gauges and some R134 refrigerant but need advice on how to use them.

Answer:I have been encouraging do it yourself refrigeration with my books for twenty years but unless the correct procedures are followed these small systems can be damaged. The key to successful troubleshooting is to begin with non destructive testing first. It must be determined if a unit that fails to cool properly is a control problem or a refrigerant system problem. It is very difficult to tell if these small Danfoss compressors are actually running because they are so quiet. Many times the fan noise is believed to be the compressor running. If it is confirmed that the compressor is running, then and only then, should destructive servicing equipment be connected to a capillary tube system.

These small units are very sensitive when it comes to servicing them with refrigerant. If the compressor is a model BD2.5 it must be serviced with R12 refrigerant. If the compressor is one of the following ,BD3, BD35 or BD50, 134a refrigerant is used.

Connecting a servicing gauge set to these units, if not done properly, can be destructive to the system. Here are some simple guide lines to follow when you question the refrigerant level and refrigerant flow conditions:

1. A system low on refrigerant may be running in a vacuum so do not connect the gauge set when it is running.
2. Purge gauge set and hose with refrigerant before connecting it. These small systems only contain 2 to 5 ounces of refrigerant and can easily be contaminated.
3. The amount of refrigerant pressure in the system when the gauge is connected is only an indication of whether all refrigerant was lost or there is still some left in the system. Pressure in a capillary tube system when it is not running is relative to the ambient temperature of all the components and not refrigeration volume.
4. If there is no pressure when gauge is connected, pressurize the system and find the leak and repair it. After the leak is repaired Vacuum system to remove air and moisture then service it with the correct refrigerant.
5. These systems are normally serviced by adding the correct volume of refrigerant by weight, but in the field when a measuring cylinder is not available they can be serviced by pressure in the suction side of the system. This pressure will very based on evaporator size, type of refrigerant and temperature in the evaporator. One ounce plus or minus from the correct volume will greatly affect the power consumption and performance.
6. If you have the small Abler Barbour with their small chamber (bin) evaporator the correct suction pressure with a 70˚ F. box and warm evaporator would be 8 to 10 psi for R12 refrigerant and 6 to 8 psi for 134a refrigerant. These readings must be reached in a time window of ten to twenty minutes after start up with a warm box. After twenty minutes suction pressure will drop as the plate temperature drops.

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8. Danfoss refrigerant charge Servicing

Hello everyone that enjoys cold beer and wants to keep there lobster tails frozen until ready to eat them. For a very long time cruising now, I have been a big fan of Adler Barbour reefer units. (Now Waeco). Also, I must add that I have had excellent help from them when I had an installation problem concerning not enough length of copper tubing to reach the compressor location. They will make you up a 5 foot pre-charged extension if needed. Anyway, being the weekend, and not being able to get thru to tech support, my question is, how much refrigerant 134a, is required for a proper charge. I was told, that you can tell by the amperage draw of the compressor that the charge is correct. This is the "Cold Machine" which is air cooled. I should also add that I have no problem, but was just wanting to know the numbers for future reference.

Answer: The only way that I can give you a ballpark guess about the current draw of a BD compressor is to know the model of compressor, BD2.5,BD3,BD35, or BD50. Then I need to know the ambient temperature of box and system and compressor speed. The best efficiency and performance of a capillary tube system like an Adler Barbour unit depends on refrigerant, evaporator superheat, and condenser’s sub-cooling.

Twenty grams under correct refrigerant charge will cause the compressor to run longer. Connecting servicing gauges to one of these fragile systems or measuring refrigerant volume by cycle times can be a mistake. The best way an owner can determine refrigerant purity and volume on air cooled Adler Barbour systems or other thin plate evaporator capillary tube units, is by viewing the frosted areas of evaporator and tubing. A properly serviced system will have frost over 95% of the evaporator’s surface on a 70˚ day and no frost on the line outside the refrigerated box. A correctly serviced fixed speed BD2.5 or BD3 compressor will draw 5amps until evaporator temperature drops to say +12 º F then reduce to around 4 amps maybe.

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9. Refrigerant Charge and pressure.

The unit-Adler Barbour CU-200 with VD-152 evaporator The question-What are the normal operating pressure ranges for this system?

Answer: The normal operating pressures on any small capillary tube refrigerator system will depend on: the condenser’s cooling medium temperature, temperature of the evaporator and the refrigerant volume. Companies that assemble these systems determine what they believe to be the correct refrigerant charge for an average application for their condensing unit and matching evaporator. The volume of refrigerant in one of these small units is listed by weight in grams. I recommend that gauges not be connected to these systems unless it is first confirmed that there is a refrigerant problem, as most of the time the quality of refrigerant is compromised by small amounts of contaminates. If compressor has been on and running for a period of time with good condenser cooling the frost line will identify the amount of refrigerant in a capillary tube system having a thin aluminum plate evaporator. Frost should be present on 90% to 100% of evaporator based on ambient air conditions and no frost outside the refrigerator box on line returning to compressor.

When using a refrigerator thermostat on Adler Barbour with 134a refrigerant the suction pressure might range from 4 to 8 psi. The same system with a Freezer thermostat can allow suction pressure to drop to zero psi and -22 degrees F evaporator temperature.

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10. New Isotherm Pre-Servicing Leak Testing

Low amperage with lack of more than 50% evaporator frost coverall confirms refrigerant charge is very low. So my question is what happened to it? Either one of the three components lost their pre-charge or a line connection you made is leaking. I believe Isotherm's line connectors are Aero Quip and use a group of O ring seals.

There is no way to determine if moisture has entered the system so the best thing to do at this point is to pressurize the system with 134a refrigerant. Purge whatever type unit you will be using to add refrigerant first. Now add only pure refrigerant gas with bottle upright till system pressure in system is equal to bottle pressure.

Use a 50/50 mixture of liquid soap and water and apply it to each connection to be tested. Agitate mixture on fitting with small paint brush to create shaving cream foam. Look for bubbles. If leak is at one of disconnects tighten it only 1/8 of an inch after it feels tight.

On a 70˚day bottle pressure in the system will be about 50 to 55 psi and enough that is enough refrigerant for the system to operate. Fine tuning of refrigerant will need to be done after unit runs for an hour or more.

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11. Different ways to service Small 12/24 Volt Refrigeration

Most manufacturers do not offer instructions for refrigerant servicing small refrigeration units that incorporate capillary tube refrigerant expansion devices because correct charge is different and critical for each design.

RPARTS BD Compressor servicing Procedure

Turn the thermostat knob to its middle position, about "3" or "4". The

fan should come on and a few seconds later the compressor should

start. When the compressor starts, the suction pressure gauge (blue)

reading will go down.

When the gauge reading approaches zero, open the service manifold

valve briefly to allow more refrigerant vapor to enter the system.

Keep regulating the valve to try to maintain about 10 psig on the

gauge. Add refrigerant slowly (a few seconds at a time) and allow

the pressure to stabilize before adding more. Only add refrigerant when

the pressure is below 10 psig.

At some point, frost will begin to form and slowly

spread around the evaporator

Keep adding refrigerant slowly until about 1/4 of the evaporator is

frosted. The low-pressure reading should be about 8 to 10 psig when

the evaporator is 1/4 frosted.

Allow the system to run until the thermostat turns it off. The

evaporator should be fully frosted, and the suction pressure reading

should be around 4 to 6 psig.

Technautics TXV sight glass Servicing Method

Technautics Cool Blue and others may use a Thermo Expansion Valve (TEV) with a refrigerant receiver tank and refrigerant sight glass. Procedures for servicing TEV systems are not the same as Capillary Tube refrigerant flow control devices.

1. After 10 minutes operation, observe the sight glass. If bubbles are present, the system needs to be charged.

2. Tightly connect the charging hose to the refrigerant can.

3. Remove the blue cap from the suction valve and very loosely attach the charging hose to the suction valve

4. Open the refrigerant can valve slightly and purge air from the charging hose for 2 to 5 seconds, then firmly tighten the charging hose to suction valve connection.

5. Open the refrigerant can valve fully to feed Freon into the system until bubbles are no longer visible in the sight glass.

6. Continue running the system for 5 more minutes and look for bubbles in the sight glass. If bubbles are present, repeat step 7.

Note: Charge system only by using the sight glass, not by using a pressure gauge. A few bubbles are OK.

7. Repeat steps 7 and 8 until no more bubbles are visible.

8. The system is now fully charged. Reset the thermostat to its previous position.

9. Close the refrigerant can valve, disconnect the charging hose, and replace the blue cap (finger tight).

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12. Servicing a Frigoboat System.

The servicing of a capillary tube system with refrigerant without system designer’s refrigerant weight measurement is a time consuming chore. Servicing by determining frost line and monitoring amperage will get the refrigerant volume close for a particular condenser cooling medium’s temperature. The system designer would select a volume of refrigerant that produces the best performance with a standard day condenser cooling medium air or water temperature of 70˚F. As the ambient condenser cooling medium’s temperature changes so will the system performance and required refrigerant volume will change.
For the BD35 compressor I have to assume the servicing equipment you bought matches the items I listed.

1. Make sure the compressor is turned off before connecting refrigerant bottle as it could be in a vacuum. If refrigerant is low, air could enter the system.

2. Install adaptor onto compressor’s suction service port located on top of compressor.

3. Connect tap-a-can servicing unit to the small bottle of 134a refrigerant. Be sure the puncher pin is backed out far enough so that it won’t puncture the can now. Next, screw T handle all the way in to puncture can, then open valve to purge the hose and close it again. The adaptor you install will have a valve inside, if this valve does not look like it is going to depress the valve core inside the compressor fitting, then the compressor valve core will need to be removed, after letting pressure out of the compressor NOTE: Wear safety glasses when working with refrigerants.

4. Connect hose disconnect to compressor servicing port.

5. With the can right side up letting only gas flow into the system, let the pressures equalize. This is done when the evaporator is warm. If done when cold the system will be overcharged. Close T valve on service tap a can port.

6. If you are able to read the amp draw after ten minutes of system running, it then should read 5 amps and no more, if not add more refrigerant. If you are not able to read amperage, wait 20 minutes and check frost level on evaporator.

7. When there is frost covering 95% of the evaporator surface and no frost returning on line outside the refrigerator the refrigerant charge is in the ball park.

If there is frost on the line outside the box it will indicate too much refrigerant and heavy power consumption.

Always add refrigerant very slowly and wait twenty minutes to check frost area of the evaporator and line. After the first 20 minutes, ignore amperage as the colder the evaporator the lower the amperage will be.

13. Cool Blue Refrigerant Servicing with an Expansion Valve

I am looking for a recommendation from you as to which of your books is most appropriate for my needs.

I have a couple cool blue 12v Danfoss based systems. I am looking for a chapter that contains detailed DIY instructions for recharging. I have attempted this in the past by using the site glass and bubbles method and succeeded in overcharging the system. A - novice error in that I didn't take enough time to let the system settle.. By trial and error (following some comments on a web thread - in which you participated) I have got it back working.  But I would really like to get it working efficiently. I am currently in Panama on the hook so DIY is the only viable option.

Answer: My 12/24 volt Boat Refrigeration Manual does not cover the detailed information you need. I operate a web forum to supplement my books with up to date revisions.

There are four different compressors used on Technautics Cool Blue icebox conversion units Danfoss BD 2.5, BD3, BD35 and ACC 12-42 volt. Technautics does not provide identification of ACC compressors but they have round compressors and Danfoss compressors are oval shaped when viewed from the top. ACC control modules have a computer serial port interface above power in spades at top of module Compressor speed on all Cool Blue units are set to run at minimum speed, Danfoss at 2000 rpm and ACC compressor at 1500 rpm. Although there are dip switches on ACC units to increase speed I am told.. The newer Cool Blue systems on display at boat shows have ACC compressors.

I believe that design of Cool Blue units are great for small boxes in cool climates but servicing with the right amount of refrigerant in a hot climate is difficult. If you follow the Technautics manual which describes using the sight glass as a servicing guide, you will have too much refrigerant in the system. My opinion is with a large Thermo Expansion Valve (TEV) and a larger than needed refrigerant receiver storage tank there probably should be bubbles in the sight glass until the holding plate is frozen solid. If one follows Technautics servicing instructions and turns system off for a few days in a hot tropical climate, it later will shut down on overload when startup is again attempted. My advice after many emails about this problem, is to place a bag of ice against the holding plate to reduce temperature/pressure in the system for a couple of hours and then the compressor will start when power is turned on.

The reason there must be a receiver tank to hold excess refrigerant when a TEV valve is used is to control the refrigerant flow and store excess refrigerant when valve throttles back closing its orifice to lower evaporator pressure/temperature. If a system has too much refrigerant and the receiver is completely full of liquid on an 80º F Plus day there will be no place for excess refrigerant to go except back to the condenser. Too much refrigerant then causes pressure/amperage to build to a point where module amperage overload occurs stopping the compressor. If the receiver is one third full of liquid refrigerant to two thirds full, the system should work fine. I would guess 8 to 10 ounces by weight is the correct amount in receiver. One report I read said Technautics advised him to add two pounds.

I would think very small bubbles even when the plate is frozen solid is going to be more energy efficient in tropical climates.

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14. Vacuum Pumps Servicing

Today’s small icebox conversion refrigeration units are more sensitive to moisture and other contaminants than ever before. This is why a refrigerant deep vacuum pump is used any time refrigerant or its oil is exposed to air or contaminant gases. Moisture can cause ice crystals that will block refrigerant flow. Moisture mixed with refrigerant and oil and other chemicals will form sludge containing hydrochloric acids. Acids moving with refrigerants tend to cause aluminum evaporator corrosion and copper items to be electroplated to steel parts.

Polyester oil now used with 134a refrigerant absorbs moisture quickly and unlike previously used wax free Mineral oil refuses to release or boil off moisture to a gas.

A good vacuum pump, which reduces internal system pressures to the boiling point of water at normal temperatures, will convert moisture to vapor gas. Vacuum pumps will not extract liquid. Water must be vaporized to a gas before it can be removed. To reach a low pressure boiling point, which is necessary to extract moisture, a deep vacuum of as close to absolute vacuum is desirable. Low pressure (blue) refrigeration gauges reads in pressure and vacuum. With a standard day’s temperature 69º F at sea level atmosphere pressure is 29.30 inches of vacuum. If ambient temperature is colder than standard then a very deeper vacuum is required or heat.

.Most blue low pressure refrigerant gauge scales indicate 30 inches of vacuum so we assume that if while vacuuming gauge reads 30 inches moisture is boiled away. Accuracy of gauges is not to be relied upon because one inch of vacuum is equal to 25000 microns. To boil off moisture most technicians vacuum at less than 500 microns of vacuum.

My recommendation for dehydrating a small system confirmed to contain moisture and having ester oil is to warm complete system to 100º F. I prefer maximum vacuum pump vacuum and temperature be maintained for four hours

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15. Another vote for Do It Yourself SERVICING

My AB cold machine model DCM-12 is, I'm pretty sure a 1989 unit. My boat is a freshwater only, Lake Michigan, 1989 Catalina 30. We bought the boat in 1992 w/35 engine hours and seemingly very little use. The fridge has performed flawlessly until this season. Before the recharge last week, it would run but not cool. After the recharge, it would cool, completely frost up the evaporator and frost up the upper refrigerant line as far as I could see into the bilge. The fridge ran continuously and would not shut off. I called the company that did the recharge and they were just here and removed about 3-4 oz. of refrigerant. He mentioned that when he got back to his shop and weighed the refrigerant installed, he thought he had put in too much. They did not bring a scale to measure the amount put in the first time. This time he brought a scale to determine how much he removed. I don't expect to be charged for the second service call. So far, so good, the fridge is cooling and cycling on and off as it used to. 

Answer: Why do you believe your unit has too much refrigerant in it? Correct amount of refrigerant is indicated by frost covering 95% of evaporator's surface area and no frost on line outside refrigerator on return line going to compressor. If there is frost on line how far does it extend? What model Cold machine is it ? Is the unit less than 12 years old? if so it has a BD50 variable speed compressor with a trouble shooting LED. If it has the LED and the compressor does not run, how many times does it flash every 4 seconds? If LED flashes 3 times every 4 seconds there is probably too much refrigerant.. Answer my questions and I will provide information for you to correct problem.

Your refrigerator story is a common screw up because on small systems like yours refrigerant is measured in grams not ounces.The one question I have is did the mechanic find and fix the leak? There must have been a leak because AB units do not normally leak.

When your refrigerant charge is correct in a cold climate the evaporator will have more than 85% of its surface area covered with frost and no frost on line outside refrigerated box.

It leak was not repaired evaporator frost areas will slowly lose frost leaveing larger and larger area without frost.

Reply: They did not do a leak test. I am hoping that it took 23 years for the refrigerant to leak a miniscule amt and it just needed a tiny bit extra??? My bill $284.00 seemed pretty big.

2hrs @ $100.00 an hour for portal to portal, $1.50 per mile and $60.00/lb of refrigerant. I have asked them to review the bill. He was on the boat for about an hour and it didn't take a lb of refrigerant. IF it is fixed and runs for another ---- years, it will have been worth the money, if not, I'll probably be buying another unit. We shall see.

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16. Standard Danfoss BD Compressor system adding Refrigerant and leak testing LOW ON REFRIGERANT

If a Gurgling sound is heard it confirms that gas and oil are moving so there is no blockage in your system. No frost on evaporator, amperage below 1.5 amps, and gas moving through system indicates lack of refrigerant.

These are the steps needed on a BD35 or BD50 compressor capillary Tube unit to re-commission your system:

1. Check gauge set to see that gauges read zero when not attached to unit if not adjust or make a note of their errors.

2. With both gauge hand valves closed, connect 134a bottle to center yellow hose. Check to see that blue gauge has blue hose and lose end of blue hose has a valve core depressor inside. Before connecting blue hose to low pressure connection open blue gauge valve for 2 seconds to purge yellow and blue hose then close valve and connect blue hose to service fitting on top of compressor.

Inspect valve cap you removes to see that rubber seal inside cap is still good. Slow leaks are sometimes traced to a bad cap seal.

3. With refrigerant bottle upright open blue gauge valve to add refrigerant. Blue gauge should now be reading system pressure of 30 to 60 psi depending on temperature of complete system. After blue gauge is connected and system has pressure in it you will need a one inch paint brush and a small amount of water and liquid dishwashing soap mixed 50/50% to locate refrigerant leak.

4. With 50 psi of gas pressure in system, use soap and water mixture to locate leak. By using brush to apply mixture to only one point at a time stabbing brush into location until a shaving cream mixture surrounds it you will break down to liquid surface tension so any leak must come through foam generating bubbles. Leak testing is done with compressor off.

5. After leak is found and repaired unit can be serviced with correct amount of refrigerant. In your situation best way to get correct charge is again raise pressure 50 psi then run compressor for 10 minutes and then and only then add refrigerant if necessary or reach 6 to 8 psi suction pressure. It is important that you not add refrigerant after 20 minutes run time as correct pressure can not be determined after 20 minutes. For final fine tuning unit needs to run for a day or more. Correct refrigerant charge for your unit is when 90 to 100% of evaporators surface is covered with frost and no frost on line outside refrigerator on line returning to compressor.

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17. Servicing Danfoss BD System after replacing evaporator

If you are replacing the evaporator, it will be necessary to pressure leak check the system connection before evacuating and dehydrating with vacuum pump. Purge gauge set and hose with refrigerant before connecting it. These small systems only contain 2 to 5 ounces of refrigerant and can easily be contaminated.

After all line connections are tight, add refrigerant gas with bottle vertical until system will not take any more refrigerant this is about one ounce of refrigerant on most of these small units.

These systems are normally serviced by adding the correct volume of refrigerant by weight, but in the field when a measuring cylinder is not available they can be serviced by pressure in the suction side of the system. This pressure will vary based on evaporator size, type of refrigerant and temperature in the evaporator. One ounce plus or minus from the correct volume will greatly effect the power consumption and performance.

Reply: Thanks again for all your help this AM. It appears to be working but we are a bit concerned that it seems to be cycling on/off every 5 min even with the thermostat at 7 and reduced probe next to box from initial install. Do you think this should run every 10 minutes instead of 5? As you recall we had a small freezer compartment with a spill over refrig via fan, etc. So we did put the bin in the freezer compartment and would like it to get a bit colder in both sections. We think this could be accomplished by having the compressor run a bit longer? Do you see any issues with taking our old "freezer rated" thermostat and swapping it out with the new thermostat. We want to switch out the thermostat but use the new wire (that has a built in resistor - 3000 rpm).Will this allow our evaporator to run longer and therefore box become colder? 

We are still a bit concerned about leaving the old filter dryer that came with the compressor in along with placing the new flared filter in but the system does work so far.

Answer: The first day in a hot climate the unit will cycle more than normal till both refrigerated areas are cooled down. If the thermostat is installed correctly and to confirm nothing else is causing the compressor to cycle, I would first remove thermostat wires at module terminals C and T and place a jumper wire across C and T. Compressor will now run continuously.

Today with compressor cycling on and off all night what is length of one complete cycle?, Minutes ON and minutes OFF.

What are temps in refrigerator and freezer areas today after running all night?

If compressor is overpowering evaporator and boxes are now colder than desired it would be more desirable to slow down compressor’s speed and reduce energy power usage.

As to the old filter the new one was installed downstream and would trap any thing that might come from old filter. If system was correctly dehydrated before refrigerant was added even the old filter’s moisture will have been removed.

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18. Frigoboat BD leaks and servicing

We own a 2003 Hallberg-Rassy 53 purchased this spring and now in the Virgin Islands. It is equipped with two 24V Frigoboat keel cooler systems; one each for the refrigerator and the freezer. The refrigerator is working fine.

After starting and running both systems for about a week after arriving in the islands(boat went south on Dockwise and this was the first time since buying her in the spring that we have run the refrigerator and freezer) the freezer stopped cooling. The evaporator that was frosted over for a week lost its ice, there was no refrigerant noise in the evaporator and the compressor was running constantly. We shut the unit off and had a refrigeration technician look at the unit. He determined that the unit needed gas and added some. He used a gas sniffer but could not find a leak. After adding gas the unit came on and began to cool. After running the unit overnight I found that temp in the box to be -10˚F(it had been holding at 0F previous to the problem), the unit running constantly, and the return line frosted back to the compressor. I then contacted the technician who told me to vent some gas. After a series of venting for 5 second bursts and observing the results I got the unit to start cycling, the frost off the return line, and the box temp to 0˚F. , I have your book on board but we are back in Colorado and I have a couple of questions that perhaps you can help me with.

The leak is still there, I presume, as it was not found. While I am waiting for the leak to get to the point that it can be found I am considering getting a set of refrigeration gauges, some R134A and a gas leak detector. The idea being to top off the system and then find and correct the leak when found. If this seems like a good idea to you could you suggest where I might want to go to purchase these items. (There are refrigeration gauges offered on EBAY @ $55; are these any good?) I have also noticed that R134A is offered in a kit for topping off auto air conditioning systems. Would one of these kits be able to attach to the compressor service port? If so, I could add refrigerant and/or purge as necessary. Good idea?
Answer: Common Frigoboat refrigerant leaks are located at service connections due to poor cap seal or at one of the line disconnects. Your keel cooler refrigeration unit has at least four line disconnects with each having replaceable O ring seals inside. If line extensions were required on your units there may be six line connectors. A few of the Frigoboat line connector O ring sets should be carried onboard as spare parts.

Finding very small refrigerant leaks on these small units is difficult. I have four different types of electronic leak detectors that their manufacturers claim can detect a refrigerant loss as little as one ounce per year. With years of experience I am able to locate leaks of more than one half ounce per week. So I do not recommend you purchase an electronic unit. Electronic testers can speed up the time it takes to find a serious leak by locating a contaminated area but pinpointing leaks and confirming them still requires a positive secondary confirming test such as soap and water. My books have always recommended to boaters that leak detection by using a 50/50% mixture of dish washing soap and water is the best way for them to find refrigeration leaks. The correct procedure is to use the tips of a one inch brush to beat the soap mixture into a suspected area until it resembles shaving cream then watch area for two to three minutes to see if bubbles begin to form. Very small leaks in suction side of system can only be located with refrigerator box warm and system off due to low pressure in this area when system is cold or running.

Servicing equipment is good, if you understand how to use it, but as you have experienced, the service person you had work on your system did not understand the process on a capillary tube system. Harbor Freight and JC Whitney both sell inexpensive gauge sets mail order. Right now all you need is soap water and a one inch paint brush, a 14 ounce can of 134a refrigerant, a tap a can available at auto stores with hose and quick-disconnect attached for 134a. The last item is a male disconnect fitting that will couple to tap a can hose fitting with a standard ¼ female flare inside to convert the Frigoboat compressor servicing fitting to accept the 134a refrigerant standard.

Correct servicing method when gauges are not available. First step is to purge servicing equipment before connecting it to compressor service port. There are two different service adapters that fit on the compressor‘s service port. You need the smaller one that snaps onto a tap a can hose. Also if this adapter’s valve core does not extend far enough to depress original valve core the original core must be removed.

Add refrigerant slowly with refrigerant can up right adding vapor only, watch amperage draw of unit and listening to compressor to avoid overloading compressor. Stop adding refrigerant when compressor load stabilizes at 4 amps. Let compressor run till evaporator has a thin frost cover. The correct charge in a warm climate will be indicated by frost covering 98 to 100% of evaporator, surface and no frost outside the refrigerator on return line. It is more energy efficient to be under charged a little than overcharged. The actual current draw will depend on efficiency of keel cooler and the preset speed of compressor. If the boat is moved out of the tropical waters additional refrigerant may be needed do to cooler water temperatures.

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19. Add Refrigerant to AB Serving Fittings

I have an ADLER-BARBOUR CU-200super cold machine system on my boat. What is the procedure to recharge the system and what is the proper low-side fitting to connect the gauges to the system? I am not aware of this system..
Answer: I always need to know why someone thinks they need to add refrigerant to one of these leak resistant systems. Many times connecting to servicing port does damage to a properly serviced small unit. Confirmation that refrigerant level is low would be compressor runs with no cooling or evaporator is not covered with frost over 85% of its surface area. If compressor stops or will not run continuously, it is not because of refrigerant unless someone has tampered with refrigerant before, the problem is electrical.

These systems are very critical on volume of refrigerant. When serviced at the factory refrigerant is added by weight in grams. In the field even service technicians rarely service these units correctly. The final result of fine tuning refrigerant level will be when frost covers 95% or slightly less of the evaporator’s surface area and no frost on line leaving evaporator. The correct level of refrigerant will change if boat is moved to a warmer or cooler climate. Manufactures service refrigerant by predetermined weight based on standard day temperatures. The SU 200 has the low side servicing fitting located above the compressor dome. Warning do not use service fitting on pressure line below compressor.

In most cases the refrigerant service fittings on boat refrigerators are still the conventional ¼ inch flared fitting as used on the older Freon systems. Only auto industry is using a different style ACME 134a fitting. Tooling for servicing 134a refrigerant on refrigerators must be adapted to older type ¼ inch fitting. There are pictures in my 12/24 volt book on different ways to convert servicing equipment and detailed information on service your unit, or any auto parts store will help you solve the tooling problem. Important things to remember:

1. Unit must be turned OFF when connecting or disconnecting servicing equipment.

2. Purge air out of servicing equipment immediately before connecting it to compressor.

3. Only add small amounts of refrigerant at a time as too much will trigger compressor electronics and prevent compressor from running. If you can monitor amperage of unit add 134a refrigerant until you see 5 amps on meter, now run unit until frosted areas are visible, one hour or more then add small amounts of 134a until frost line is correct.

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20. Servicing small 12 volt units by frost level with correct Refrigerant

I have received your book and am ready (and certified) to embark on a R12 recharge of my system.

I do have a question (or two).

Most of the R12 cans/hose I see on ebay use a single blue tap-a-can setup w/no gauge.  Is this acceptable for the type of recharge you advocate?

Second, I believe your instructions were to add refrigerant slowly until the evaporator frosts over.  Your book references that you need to do this after 10 minutes of system startup and then within 15 minutes after that.  Will the evaporator frost up within that time period?  My impression was that the process you described was considerably slower paced that than.

Finally, does purging the single blue line involve opening the value at the tap part for a second or two.  And then do you attach the hose to the servicing port?  Will there be small amount of air trapped in the hose fitting and serving port cavity?  Could you partly thread the fitting onto the serving port then purge thereby displacing the air in the fittings?
Answer The procedure below without gauge takes longer than the one in the book with gauge. It only takes a few minutes for evaporator frost to form. As long as you can detect frost all over the evaporator on your finger nail, refrigerant volume is good.

The servicing of a capillary tube system with refrigerant in the book is intended to be used with gauges.

1. Make sure the compressor is turned off before connecting refrigerant bottle as it will be in a vacuum if low on refrigerant.

2. Connect tap-a-can servicing unit to the small bottle of correct refrigerant. Be sure the pin is backed out far enough so that it won’t puncture the can and be careful not to over tighten can as it will dent the top of can and break the seal area. It is better that this connection is not tight as if it leaks when bottle is punctured it can then be tightened a little.

1. Now screw T handle all the way in to puncture can, then open valve to purge the hose and close it again

2. Connect hose to compressor servicing port

3. With the can right side up letting only gas to flow into the system let the pressures equalize. This is done when the evaporator is warm if done when cold the system will be overcharged.

4. Start the compressor with valve open for 15 seconds then close.

5. If you are able to read the amp draw after ten minutes it then should read 5 amps if not add more refrigerant. If you are not able to read amperage, wait 20 minutes and check frost level on evaporator.

6. When there is frost covering 100% of the evaporator surface and no frost returning in the line outside the refrigerator the refrigerant charge is in the ball park.

If there is frost on the line outside the box it will indicate too much refrigerant and heavy power consumption

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21. Refrigerant. Charge AB Adler Barbour Forum archives

This is a reply to R-12 Cold Machine forum question pressures
Answer Submitted WAECO USA on 12-12/01 at 08:11AM regarding General interest

With a small evaporator (freezer bin which measures 10"x6"x11") ambient running pressure should be 8 PSI (R12). The large evaporator (15"x6"x12") should be 12 PSI. After cycling begins, small evaporator should be around 5 PSI, large 7 PSI.

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