Refrigeration Compressors:
What's Causing That Terrible Smell?
Refrigeration compressors can make you gasp for air. Your nose begins to burn and you quickly turn away!!!
The service call was for a down cooler. Walking onto the roof of a packing plant, I noticed the condensing unit was not running.
Not only was the condensing unit off, so was the evaporator air handler. My first thought was no power.
It didn't take long to find the tripped breaker. But what caused it to trip?
I never reset breakers on high voltage equipment until I check for grounded equipment!!! High voltage does scary things going to ground.
Starting at the heart of all refrigeration equipment, I decided to ohm the compressor motor windings.
My suspicions were correct. I had a grounded compressor!!!
As I attached my refrigerant gauges, a terrible but very familiar smell surrounded me. I quickly turned my head.
No doubt about it. The compressor was not only grounded, but had a severe burn-out!!!
What's a burn-out?
When the motor windings in semi-hermetic refrigeration compressors go out, the motor can literally burn!!! Have you ever smelled burning refrigerant?
Ever heard of phosgene gas??? It's a deadly gas generated when refrigerant burns. The good thing about phosgene? You know when it is around.
Your nose, throat, and eyes begin to burn. It takes you breath away.
What other problems will you find when dealing with a burned out compressor?
That clear, pale yellow, refrigerant oil, comes out of the compressor black as coal. Very nasty stuff. Don't get it on your hands. If you do, wash it off quickly!!
Burnt refrigerant oil is very acidic!!!
Not only the compressor but the entire system can be contaminated!!! Sometimes very little but many times the contamination is very severe.
What's the proper procedure for cleaning a refrigeration system?? First replace the oil and install removable core filter driers. Then change them often until the refrigerant oil is acid free.
Acid test kits are readily available.
Guess what!!! I've found the above procedure practically useless!!!
Want to know how I clean a system? Change the compressor oil repeatedly. Sometimes in severe burn-outs, 10 or 12 times!!!
When the oil is once again that lovely clear, pale yellow, the system is clean.
Now I install new filter driers.
It is a much quicker method. The oil returning to the crankcase washes the system. Clean oil, means clean refrigeration system!!!
Refrigeration compressors generating poisonous gas and acidic oil!!!
Why do I love this trade??? Someone please remind me!!!
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