Compressor Problem

[jakb21599]

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

[chemi-cool]

Broken valve.

You will need to repair it or replace it.

[Sandro Baptista]

Replace the valve plate

[jakb21599]

Would the broken valve affect the SH and SC ? Would it affect the low and high side pressures ?

[Sandro Baptista]

SH does means superheating?
SC does means??...subcooling??

[Sandro Baptista]

"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.

[jakb21599]

SH does means superheating?
SC does means??...subcooling??

Yes SH - superheat. SC - subcooling

[Sandro Baptista]

yes, my opinion is that superheated is affected. About the subcooling I can see a direct reason to be affected.

[Sandro Baptista]

I meant the non useful superheated tends to be higher.

[padraic]

valve plates..!

[THE DUDE]

Pull the head, there may be more damage than expected....but most likley just a Valve Plate.

[mark957]

hello
if the oil pressure is good, it is convenient to replace the valve plates.
hello and good luck.

[aramis]

Broken valves reduce compressor capacity and you cannot adjust well because the components behave as if they were oversized.

[D.D.KORANNE]

Valve plate gaskets might have blown off .........in any case head will have to opened to check valve reeds / plates .......