Adler Barbour Refrigeration Performance and Recharging After reading the articles in this section I would like to offer some tips on small12-volt refrigeration units using the Danfoss compressor. ARTICAL The R-134 refrigerant is not as efficient as the R-12 was, but the box has always stayed cold (at a higher setting number on the dial). My old unit would freeze my beer if I set it above #4 on the dial, the new one has to be set at about #6 to maintain a 40 degree temp in the box. To make a long story short, I've had to run up the adjustment lately just to keep things cool and now I have it set on #7 (MAX) but the unit is running constantly. COMMENT On a standard Adler Barbour Cold Machine the small cap tube from the thermostat is clamped to the Evaporator chamber. The amount of this tube contacting the evaporator will set the range of temperature hopefully providing the desired temperature in mid range. The range can be adjusted by clamping more or less tube under the bracket. Repeated cycling of the compressor in this systems design is normal and it may cycle 50 to 120 times a day with no product in the box. This cycling is a result of the cooling energy being produced in the evaporator at a greater rate than the heat in the box can be absorbed. A normal properly serviced and properly installed system should develop frost over the complete evaporator within a few minutes. This frost may not be visible at first but can be picked on a fingernail. The difference between R12 and 134a should not be of concern. Tests that I have done show the 134a in the BD 3 out performs Freon under standard day conditions. The key to this owner’s complaint seams to be that the unit does not cycle when the thermostat is set to full cold. It the cooling airflow across the condenser is good and is no more than 90 degrees F. The problem is the refrigerant charge. A lack of frost on the evaporator indicates a lack of refrigerant. With too much refrigerant there would be too much frost on return line. ARTICAL Charging the refrigeration system. I appreciate all of the input. I pulled a vacuum on it this weekend and put a little, and I mean a little, R-12 in it. Within a couple of hours the surface temp on the evaporator was 18 degrees. After 5 hours the compressor was cycling on / off 50/50 and the box temp. Was down to 42 degrees. The evaporator surface was "tacky" to the touch due to a very thin frost layer. Outside temp. was about 100 degrees on Saturday. I still have a couple of questions..... What is the best way to dispense 3.5 oz. of R-12 without overcharging? Is there some trick to this or do you just carefully meter it in by holding the can of freon in your hand and judging by weight? That's all I did. Also, if the compressor cycles on and off with the box temp. at 42 degrees on the coldest setting with the outside temp hovering around 100, is that acceptable performance? I'm think that the thermostat is shutting the compressor off before it is reaching the coldest possible set point. I was hoping to get the box down to a true 40 degrees, maybe even 38. If the thermostat is set to the coldest setting, shouldn't the compressor keep on running? Shouldn't the maximum setting be lower than 42 degrees? One last thing, I hear a little gurgling and "groaning" sound in the refrigerant lines when the compressor is running. They aren't vibrating or rattling, it actually sounds like the gas itself inside the lines that is making the ghostly noise as it moves in and out of the evaporator. Any ideas? COMMENT All expanding gas refrigeration and air conditioning systems operate the same by compressing a gas then cooling it to a liquid. This liquid under pressure is released through an expansion device to start the cooling process. The secret to an efficient transfer of heat is to have the correct volume of clean moisture free refrigerant. Where these little units differ from their big brothers is in their expansion devices and ability to store extra refrigerant. Large units have refrigerant storage tanks called receivers. If the receiver is full or at least has some refrigerant in it the refrigeration system function is normal. The larger units also have variable expansion devices. Because these small refrigeration units use fixed expansion tubes, the volume of refrigerant when servicing must be exact. One eight of an once will make a difference in the units performance. These units are precharged by the manufacture with a specific volume of refrigerant any loss during assembly means loss of performance. There are those who say they can tell by the sound of the expansion device ‘gurgling’ how much refrigerant is in the system, I don’t believe this. In the boat the only way to adjust the refrigerant level is to use a servicing gauge. SIMPLE TROUBLE SHOOTING CHECKS If our small system is not cooling as it once did and it has not been serviced recently there are a few simple check that can be done by any non-technical person: Check to see if there is a film of frost over the complete evaporator chamber it there is maybe the loss in performance is not the units fault but an added heat load to the box from air leakage. With low levels or no frost continue to check system. Check to see if the unit is running continuously. The noise you here is the fan. To check to see if the compressor is running you must touch it and feel a small vibration. On boats equipped with amp. meters the compressor load will add 5 to 6 amps when running. Cycling of the unit on and off may indicate low voltage and not a problem with the refrigeration unit. If the compressor and fan are running continuously, next check to see that the air passing through the condenser is not restricted with hair, lint or some other material. After the above checks OK the problem must be refrigerant level or pumping process. WHAT TO DO ABOUT INTERNAL TROUBLE SHOOTING AND SERVICEING Before going any further a decision must be made as to weather to attempt the repair yourself, call a service repair man or replace the unit. Reasons why it might be wise to replace the complete refrigeration unit over repairing the old unit: It the unit has lost all of its refrigerant and is over seven years old and showing signs of corrosion on the evaporator replace it. The unit is over ten years and you are planning extensive cruising out of the country replace it. If repair costs exceed ½ the cost of a new unit replace it. If you call a service man make sure he is familiar with the unit you have and ask if he has the service instructions from the manufacture of your unit. A one Hour service call will identify the problem as: 1 System low on refrigerant and there is no such thing as normal seepage on these units therefore there is a leak to find and correct. 2 Blockage in the system either ice or a permanent blockage of the capillary tube. Dehydrating out the moisture, which somehow got into the system, can only clear up blockage due to ice. 3 Compressor read valve failure, this is very unlikely ENTERNAL TROUBLE SHOOTING AND SERVICING We are now at a point in the trouble shooting process where special tooling and mechanical knowledge are required. Before proceeding it must be determined what type of refrigerant is in the system Freon R12 or the newer type 134a. The type of refrigerant should be marked on the compressor label if older than 6 years it uses R12. Replacement refrigerants are not recommended. The next item on the compressor to identify is the service connection. Adler Barbour I believe is the only manufacture of boat Refrigeration systems that did not provide a service fitting until the EPA required them in 1996. A good serviceman will solder a service fitting to the suction side of the system. A/B does sell a servicing gauge that can be installed in the suction side quick-disc-connect line. The only other option is to install a Piercing Valve that clamps to the line these generally leak with age and are considered a Shade Tree repair. After obtaining at least a pound of the correct refrigerant, a compound low-pressure refrigerant gauge that can be connected to the system service port, you are now ready to test the system. Testing procedures The compressor is not running and the complete system inside and outside the box must be between 70 and 80 degrees F. to service it properly. Check pressure gauge to see that it reads 0 before it is connected to the system. Accuracy of the gauge is important between 0 to 13 psi. Warning follow safety instructions on refrigerant bottle and gauge set, Eye protection is necessary. Connect refrigerant bottle to gauge and open valve to purge air from hoses before connecting it to suction service port. The end of the servicing hose that connects to the servicing port must have a valve core depressor in it to open service valve. Do not add refrigerant. The gauge should know be reading a pressure above zero unless there is no refrigerant in the system If pressure is zero add refrigerant to raise pressure in system to 30 psi and look for leak. The compressor is not running. If the leak is small use soap and water to located it. Once the leak is found and repaired a refrigeration vacuum pump will be required to clean out the system. If there was some pressure in the system to start with but less than 40 psi. add refrigerant until the gauge reads 40 psi and start the compressor. The 40-psi. will slowly decrease if it goes below 6 psi. add refrigerant within the next 15 minutes the pressure needs to be adjusted to 8 to 10 lbs. for a small evaporator and 11 to 13 for a large evaporator Attempting to adjust the refrigerant level after the first 15 minutes will provide poor performance as the colder the box the lower the pressure. Richard@Kollmann-marine.com http://wwwKollmann-marine.com