Annoying Problem

[Rick D]

Richard, I have an AB system on both my refrig and freezer (seperate). About 10 years old. Thin coldplates. The refrig <seemed> to take a longer cooling period gradually. So, my refrig guy came out and indicated he added 3/4 pound of 134-mix. Four days later, I went to the boat to find the refrig warm and the compressor stalling. By that I mean the kind of sound you might get with a low-voltage condition. You can hear the fan kick on, but just a buzz from the compressor and it kicks back off. I let it sit overnight, and it ran fine for five days, cooling fine. I left the boat on shorepower/charger for two weeks and returned to find the compressor stalling again and box warm. My AC guy says he didn't think it was an overcharge which I considered because it wouldn't act like that. He suggests checking the voltage at the compressor first since he can't fit me in for a couple of weeks. He said the alternative is likely the compressor itself since ten years is about the service life. I think it's odd that it seemed to work fine before his (new) assistant worked on it and suddenly the compressor stalls. What's your take on it? Your timing is perfect, Rick Dinon

 

[Richard Kollmann, Kollmann Marine Inc.]

RE: Pay Twice Troubleshooting

A ten year old Adler Barbour cold machine would have a Danfoss BD 2.5 compressor. Is this the compressor model that you have? When you say a thin cold plate I assume you mean an aluminum evaporator and not a plate with solution in it. When one of these air cooled units takes longer to cool, the first thing to check is the air flow across the condenser. Was it cleaned and performance rechecked before adding refrigerant? The AB units about ten years ago had the fan in front of the condenser and in order to vacuum the dirt out of the coil the fan must be removed.The electronic module that controls and protects the compressor will stop the compressor if there is an overload. Poor air flow through the condenser or a refrigerant overcharge will cause an overload and stop the compressor. It is also possible that low voltage or a faulty fan will keep the compressor from running. Here are my concerns: ¾ of a pound of refrigerant is too much for that system.Why did the system need refrigerant and was the leak found and repaired?If the compressor is a BD2.5 adding 134a refrigerant to it was a mistake.Refrigerant 134a is the correct refrigerant for the BD 3, BD 35 and BD 50.Recommended Corrective ActionIf the compressor is a model BD 2.5, have the refrigerant removed, evacuated and re-serviced with Freon R12 and no substitutes. If the compressor is a BD 3 and the condenser is clean, reduce the refrigerant charge to the correct value.The problem you are describing is a common occurrence today in boat refrigeration as the repairmen are not trained in these types of problems. See the item on my web site forum on; Save from $50 to $2000 on refrigeration repairs. As you will see from my answers on your forum this week I am not trying to push my 12/24 Volt Refrigeration Manual, but in your case I am sure it might have saved you at least five times the book’s cost.