What keeps a compressor from "slugging" right after turn on

Question

I know from reading that it is bad for a compressor to try to compress liquid refrigerant. I also know that when the compressor cycles off, the refrigerant will migrate away from the warm parts of the system and into the colder parts. So during the off part of the cycle the refrigerant will migrate out of the compressor and out of the condenser and tend to condense and collect as liquid in the evaporator. So what happens when the system cycles back on. Why doesn't the liquid that has collected in the evaporator get sucked into the compressor and damage it when the system cycles back on.

The question seems to apply to both automotive and hermetic compressors.

thanks Mark

new jersey · Accepted Answer

Markyou practically answering you own questionOn off cycle liquid collects into evaporator and on start up of next cyclethere is nothing stopping or delaying for that liquid getting into crankcase ofcompressor so you wind up with busted valves among other things,solving problem of slugging is by adding suction accumulator on suction line,other two items can also help by adding crankcase heater and solenoid onliquid line, for small AC units I would say number one would be of addingsuction accumulator if space permit second solenoid and third crankcase heaterif you AC is to be used with cold temp. outside then it would be imperative toadd crankcase heater and suction accumulator!TonySo what happens when the system cycles back on.why doesn't the liquid that has collected in the evaporator get sucked

Stormin Mormon · Answer

Crankcase heater, for central AC. For window units, mostly dumb luck.

Zyp · Answer

Close but no cigar.  Only a cigarette.  LOL

What keeps a compressor from "slugging" right after turn on

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