I got a job at a big resturant doing mantinance. Things mostly for the building but just recently there has been several small coolers down and owner asked me if I can fix them. He has a refrigration company do repairs and maintaince but they are not cheap. I looked at coolers and all of them have dead compressors. One of them is locked up another shorted start winding and thrid one a grounded run winding. All of these coolers where r12 and one time and now where converted to either r134a or mp39. These comprssors are 1/3hp.
The owner is upset because most compressors are 2-3 years old and the orginal ones lasted longer than that he said. Also just before these compressors died the refrigration company replaced the compressor in a big preptable. A month ago the thing stoped working. I looked at it also and found a leak where the low cutout switch is piped. I told the owner what it was and he called the company up because its under warrenty. They came and said the compressor was bad and its under warrenty. But he had to pay the labor to change it because the compressor is only under warrenty. I told the company that the compressor went bad because there was a leak and the thing was sortcycling. They denied everything and charged 580dollars. Boss was pissed because the labor was more than first bill. They worked on a Sunday. This is a big sore spot for the boss.
I told my boss just get new coolers but he dosent want too. He says it would screw up the kitchen because of how everthing is custom built. Also these coolers are stainless and used as a tables. He is willing to pay me extra but I dont want to do the job if I am going to do it wrong.
I have changed compressors in my own stuff and never seem to have problem. It seems the most of these compressor died because of dirty condensors. Here are my questions.
Would it be better to covert them back to 12? Reason is the compressors lasted a lot longer and the mineral is more forgiving when the temps are high and everything was sized for 12.
Should I stick to 134a and put expansion valves in and figure some saftey device to kill the compressor if an overheating is present?
Is this just totaly bad idea??