Oil Pressure

**HJ Controls** · 01-11-2013, 07:15 PM

Technical Systems M# 20A0CS40 460 VOLT Condenser, Dunum Bush Air Handler very old. Copeland compressor model 6DS3R40M0-TSN-800. epr, suction acculator, reciever and hot gas defrost.

I am running 40 # suction 225# head pressure. 11 sc and 15 sh. 2 unloaders. Room temp to maintain 35 degrees. I have 2 systems and both are doing same thing.

My problem is loss of oil pressure. Solenoid holds on pump down, compressor valves do not leak by. 1 Unloader unloaded all the time the other unloader loads and unloads. oil foaming slightly when fully unloaded and a lot of foaming when partial unloaded. crankcase hot.

Any suggestions. Are these comprssors use hot gas bypass can you change to suction cutoff. i am stumped. Oil pressure never gets over 15# net oil pressure then will go to 10 and 5 at various times.

Any suggestions would be appreciated.

**Blackmira** · 01-11-2013, 07:27 PM

Sump screen clean?

**jpsmith1cm** · 01-11-2013, 08:17 PM

Originally Posted by Blackmira

Sump screen clean?

Excellent place to start.

**Phase Loss** · 01-11-2013, 10:46 PM

How does the oil taste?

**HJ Controls** · 01-11-2013, 11:12 PM

I think it has to do with the crankcase being to hot and thinning out the oil? I need to know if these compressors use suction cut off unloading or just bypass. I got 2 systems doing the same thing and one compressor is fairly new. But it could be the screen and thats one thing i will check.

**jpsmith1cm** · 01-12-2013, 06:07 PM

Originally Posted by HJ Controls

I think it has to do with the crankcase being to hot and thinning out the oil? I need to know if these compressors use suction cut off unloading or just bypass. I got 2 systems doing the same thing and one compressor is fairly new. But it could be the screen and thats one thing i will check.

While thinning oil is a possibility, I seriously doubt it.

Start with the screen. Move to the pump.

**markettech** · 01-19-2013, 11:16 AM

Originally Posted by Phase Loss

How does the oil taste?

With its taste buds, I would suspect.

**remanworld** · 01-21-2013, 02:45 PM

Copeland hasn't used bypass style unloading for many years. The compressor you are asking about is the new Copeland model number meaning that it can't be very old. What happened to the last failure? The screen probably is plugged, but the contaminants are from the failed connecting rods. The low oil pressure is the result of worn rods caused by oil that is extremely diluted with liquid refrigerant. You need to address the floodback problem and prevent another compressor failure.

**Tommy knocker** · 01-22-2013, 08:40 AM

Had a TS chiller, believe it has same comp, doing same thing. Comp had been replaced, by different company, previously. Ended up finding oil log was the problem. Pulled 6 gal of oil out of it and cleared rite up.

**remanworld** · 01-22-2013, 11:00 AM

I don't understand. How could a high oil level cause a low oil pressure problem? Did something else change in addition to you removing the extra oil?

**Tommy knocker** · 01-22-2013, 12:47 PM

I know rite? What we had was oil logged cooler/evap which caused flooding which foamed the sump.

**Push It** · 01-22-2013, 01:41 PM

Originally Posted by remanworld

The low oil pressure is the result of worn rods caused by oil that is extremely diluted with liquid refrigerant. You need to address the floodback problem and prevent another compressor failure.

How could he be having floodback when his SH is 15*F and the crankcase is hot? Do you mean flooded starts?