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New compressor with low capacity


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jsg001
New User

Jul 12, 2020, 10:56 AM

Post #1 of 4 (103 views)
  post locked   New compressor with low capacity  

First, let me thank you for any help you can provide.

I have a 2009 Pontiac G8 (6.0L, 128k miles) with a variable displacement AC compressor that typically is only driven a few times a month on nice days. Starting last year in hot weather, over 90 Deg F, the AC acted intermittently but was not low on Freon based on gauge readings while working. Recently it stop working completely. The compressor seemed to be at fault with only about 15psi difference between the low and high side despite the control signal measurement at 100% commanded capacity.

I took a broad approach and replaced the expansion valve, condenser, filter/dryer, and AC compressor. I balanced the oil and recharged the system (20.5oz of R134a), but it still only achieved a 15-25psi difference about the static pressure.

I’ve driven the solenoid control signal externally and see only a small change in pressure from 0 to 100%.

After seeing that, I opened the system again and blew all the line out and drained the oil. No debris was in the system. Nothing seems blocked; the accumulator flowed compressed air freely. I change the expansion value only because I had another and wanted to do something different. After recharge, the outcome is the same.

Temperature: 85F
Static pressure: 88psi
Running low side: 75psi
Running high side: 100psi
Solenoid near 100%

My thought is the new compressor I bought is bad. But, I’m asking for help in looking for things I have missed or misinterpreted.

Thanks,
john


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 12, 2020, 11:36 AM

Post #2 of 4 (99 views)
  post locked   Re: New compressor with low capacity  

Regardless of what you replaced, those pressures indicate either a bad compressor or you have both valves open on the gauges.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jsg001
New User

Jul 27, 2020, 9:19 AM

Post #3 of 4 (38 views)
  post locked   Re: New compressor with low capacity  

Just an update... Installed another new compressor and everything is working as expected. Without knowing what was wrong the first compressor, I re-flushed the system and reassembled with new seals and filter/dryer. It's "cool" to drive that car now. Cool


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 27, 2020, 10:09 AM

Post #4 of 4 (34 views)
  post locked   Re: New compressor with low capacity  

Glad to hear you got it resolved.

Closing this now as solved.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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