View Full Version : Compressor Problem

14-03-2012, 01:01 AM
I have a semi-hermatic compressor that when valved off it will not pull into a vacuum. If you cut the compressor off, the low side will jump up to what ever the pressure is on the high side with in less than a minute.The dairy case is keeping temperature but i can not get the SC and SH right on it, and it has higher than normal head pressure for 404A . Would it not pulling a vacuum when you valve it off cause SH and SC issues ? What other problems would it cause ? Thanks for your help

14-03-2012, 05:15 AM
Broken valve.

You will need to repair it or replace it.

Sandro Baptista
14-03-2012, 10:41 AM
Replace the valve plate

14-03-2012, 12:11 PM
Would the broken valve affect the SH and SC ? Would it affect the low and high side pressures ?

Sandro Baptista
14-03-2012, 01:15 PM
SH does means superheating?
SC does means??...subcooling??

Sandro Baptista
14-03-2012, 01:19 PM
"Would it affect the low and high side pressures ? "

Yes, since it promotes an equalizing tendency (due to internal by-pass). As consequence the low pressure tends to be higher (so the evaporating temperature will be higher less capacity to the evaporator). Also the discharge superheating will be higher since the suction gas will be more superheated.

14-03-2012, 02:03 PM
SH does means superheating?
SC does means??...subcooling??
Yes SH - superheat. SC - subcooling

Sandro Baptista
14-03-2012, 02:27 PM
yes, my opinion is that superheated is affected. About the subcooling I can see a direct reason to be affected.

Sandro Baptista
14-03-2012, 02:27 PM
I meant the non useful superheated tends to be higher.

14-03-2012, 10:17 PM
valve plates..!

08-04-2012, 11:46 PM
Pull the head, there may be more damage than expected....but most likley just a Valve Plate.

09-04-2012, 10:49 AM
if the oil pressure is good, it is convenient to replace the valve plates.
hello and good luck.

09-04-2012, 09:12 PM
Broken valves reduce compressor capacity and you cannot adjust well because the components behave as if they were oversized.

10-04-2012, 11:20 AM
Valve plate gaskets might have blown off .........in any case head will have to opened to check valve reeds / plates .......