Pressurized Crankcase

[basser]

Altan, IF the crankcase is pressurized, that means the crankcase pressure is higher then the suction pressure (bad news).

During normal operation, the oil returning to the compressor comes through the suction line and enters the motor end of the compressor. Now it flows across the motor through a check valve and into the crankcase. When the crankcase is at a higher pressure, the oil flow is reversed through the check valve and the valve will close, that is its function. As a result of the valve closing it prevents any further oil returning to the crankcase until it the valve reopens).

When you added oil into the suction line, IF the crankcase was pressurized the oil could not enter into the crankcase because of the closed check valve. This oil will stay in the motor compartment until it is pumped out or the compressor shuts down. Once the compressor is cycled off the check valve will open and now you will see the two oil levels (motor end and crankcase)equalize.

[healingair]

This to Basser,
Your explanation of oil flow/oil check valve on copeland compressors was well stated. It's scary to be standing beside a compressor and witness just how FAST an oil charge in the crankcase goes bye-bye. On a somewhat different note I've also seen an 800lb liquid receiver with a 600-700lb charge lose 75% of its liquid in less than 45 seconds with improperly set condenser fan settings. Low ambient but not on defrost. Little wonder so many compressors go south.

[condenseddave]

Originally posted by healingair
This to Basser,
Your explanation of oil flow/oil check valve on copeland compressors was well stated. It's scary to be standing beside a compressor and witness just how FAST an oil charge in the crankcase goes bye-bye. On a somewhat different note I've also seen an 800lb liquid receiver with a 600-700lb charge lose 75% of its liquid in less than 45 seconds with improperly set condenser fan settings. Low ambient but not on defrost. Little wonder so many compressors go south.

Healingair, my old signature line here was:

Refrigerants don't kill compressors, technicians kill compressors with help of dirt, heat, and lack of knowledge.

It's really very little onder why compressors fail, but what's even more fascinating are the amount of them improperly condemned...

[smilies]

Originally posted by healingair
I've also seen an 800lb liquid receiver with a 600-700lb charge lose 75% of its liquid in less than 45 seconds

I've seen 1000# receivers lose 1500# of charge! AZ-50 at that. (not meant as a "my d1ck is bigger than yours" comment)

Tech sent to r/r pressure control on compressor on a rack of 6 in April. In July evap condenser blows fuse. All comps shut off on high head except for this one, which blew the relief on receiver. Turns out the "tech" hooked the low control to the head and the high control to the crankcase. Swears he tested it.

Same tech hooked up a cfm control as head control on another comp. Says comp was running when he left. Control was set for 350# so I doubt it came on for him. Luckily it was caught in a p.m.

Same tech also hooked up the Demand Cooling sensor to the crankcase on another rack. He's still with us.

[Milk man]

Holely refer crap. I glad you didn't dilute my thread with this nonsence.

I'll have to reread this and print it myself when it's not 12am. Looks like good information.

What was my thread about anyway?

[condenseddave]

Originally posted by jerrycoolsaz
He's still with us.

Sure, he sells lots of parts.

And generates more service ork.

And has pictures of your service manager in a chicken suit with the ass cut out.