My '92 Z28 recently started making a "groaning" noise when the A/C compressor is running and the engine speed drops. (running at 2000 RPM - then close throttle to idle) - groaning noise through system heard inside the vehicle. Sounds like its coming from inside the evaporator. I replaced the expansion valve thinking it was clogging at low compressor speeds and recharged the system. Makes 43 degrees in the car but the groaning noise continues. Plenty of oil in the system and recharged to 2.25 lbs with Freeze 12. Not really that concerned about A/C but need the defroster in colder months. Any ideas or suggestions appreciated!

Thanks, John

 

Does your system not require 134a?

 

My '92 blower box and compressor Harrison stickers both call for R12. I'm afraid to go to a shop because they'll want to convert it to R134a - too much $$$!

 

I'm sorry.I did just scan this.I had looked at a previous post for a '95.Converting to 134a isn't that bad at all.Either way freeze 12 is still a good product.Sounds like you have a compressor going bad to me.Do you have high pressure readings?

 

When the A/C compressor clutch kicks in, a solenoid is supposed to also kick in to increase idle speed. If it doesn't you will hear the compressor groan. To test this, increase the idle speed a little with the gas pedal when the compressor kicks in. If the groaning sound stops, then low idle speed is the culprit.

 

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