Expansion valves have caused the death of many compressors!!!
"What do you mean I've lost another compressor!!! That condensing unit has always given me problems!!!
The store owner was not very happy when I gave him the news. I had just recently began taking care of his commercial refrigeration equipment.
I was surprised!!! Another compressor!!! Continuous problems!!! No wonder he was upset.
Something was not right.
After firing up the new compressor, it didn't take long to find the reason.
At first all appeared normal. But as the condensing unit ran, I began to notice sweat slowly forming on the compressor body and heads.
Before long the entire compressor was dripping water and cold to the touch!!!
Sweat on the suction line. OK. Sweat on the suction bell. OK. But sweat on the entire compressor body all the way to the heads??? No way!!!
Where did my suspicions immediately turn? You guessed it!!! The expansion valve.
This had every indication of a flood-back condition.
What's a flood-back? A flood-back occurs when the valve was not properly metering the refrigerant. Liquid begins entering the compressor.
When this happens it creates havoc!!! It can break valves. It can break pistons. It can break the crankshaft.
It washes refrigerant oil out of the crankcase. Eventually the compressor can seize up.
The oil pressure safety control trips out continually. I've even seen these controls bypassed by inexperienced technicians!!!
What could cause expansion valves to flood-back???
Start with the simple things. Was the correct valve installed? Was it changed out later with the wrong valve?
Check with the equipment manufacturers. What size valve do they recommend?
Perhaps someone cranked the superheat open. I've seen this happen. Why open it all the way?
In an attempt to get as much refrigerant as possible in the evaporator. Make it cooler quicker!!! Right!!! WRONG!!!
What about the power element sensing bulb? Has it been properly installed in the correct location? Is it strapped down tightly?
A dangling bulb in a warm location can cause liquid to flood back to the compressor!!!
Repeated compressor failures? Sweating compressor body? Now you know where I start!!!
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