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ridgevilleac 06-26-2008 10:57 PM

40 ton CARRIER split
Alright guys. I have a 40 ton split carrier. It trips out on the oil pressure switch. Unit will run about 2 days and trip again. I've unloaded to the condensor several times but it keeps loosing its oil. The unit has been in service for 16 years with a new compressor 2 years back. The unit has a 7/8 discharge and a 2 1/8 suction trapped at the condensor. Crankcase pressure is 78psi suction is 62-65 discharge pressure is 220 with an ambiant of 95. I know you guys have the answer. Please Share

8 Ball 06-27-2008 05:12 AM

Sounds like your charge is low. Unloaded at 95deg. suction should be around 80 psi.. Are there bubbles in your sightglass?

Check your superheat, and adjust your charge accordingly. There should be a chart reflecting the proper subcooling on the door.

A 40 ton AC is nothing to play with. Verify that you have the proper airflow accross the evaporator before you do anything.

ridgevilleac 06-27-2008 09:25 PM

Sightglass is clear after running 2 min. Superheat is at 22. No S Heat chart available. It sounds right to me?????not even a schematic. I got inside the air handler and found some restriction and cleaned with cond cleaner (non acid) the best I could. I still think the Evap could be clearer. Anyway I went up 6 degrees on suction. I'm thinking insufiecent air flow too. Liquid washing the oil out, by lack of air????????I'm crossing my fingers

biggles 06-28-2008 05:31 AM

with that ambient hitting that condenser ,you should be easily be in the 260 PSI or higher fully loaded...your evap could be giving you that low suction (hows the return air temp hitting the evap) and move the oil out.get that discharge up to reflect the days temp and the suction will follow...might want to clean your condenser just for piece of mind prior to charging FORGET the sightglass being clear:whistling2:,get that HI side up.

8 Ball 06-28-2008 09:38 AM

Verify your airflow before you do anything. Min. 400 cfm per ton.

ridgevilleac 06-30-2008 08:43 PM

Seems cleaning the Evap has cured the oiling issue. It ran all weekend and started again this morning. The oil site glass has remained on the mark.:thumbup: Thanks for all the input guys!!

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