Automotive Air Conditioning Information Forum (Archives)

BajaScout on Sat October 01, 2011 10:42 PM

Year: 1998
Make: Chevy
Model: C1500
Engine Size: 5.7
Refrigerant Type: R134A
Ambient Temp: 80
Pressure Low: 31
Pressure High: 176
Country of Origin: United States

1998 Chevy C1500 w/5.7L. Replaced the main AC hose (accumulator-compressor-condenser) and the orifice tube. Pulled a vacuum to about 280 microns. Added two cans of R-134A and 3 ounces of oil. Nice cold A/C now, but there is a moaning/groaning noise around 2500 RPM. I goes away around 3500 RPM. I can hear the compressor clutch disengage when the noise goes away. If I jumper the pressure switch the noise will stay there after 3500 RPM. Gauge readings with the car not running are L-87 H-95. With the car running L-31 H-176. Any idea what the noise might be? The noise correlates with the RPM. Faster RPM the noise pace picks up. It isn't real loud but you can hear slightly when driving. Doesn't sound like a mechanical noise. I put a hose to my ear and to the compressor and could not ID the noise coming from the compressor.

TRB on Sun October 02, 2011 3:37 PM

Make of compressor? Sanden have a rumble to them. Low oil sometimes will cause this issue. Poor quality compressor can also be something to consider.

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BajaScout on Sun October 02, 2011 6:53 PM

The make of compressor is AC Delco. I had it replaced at the Dealer about 5years ago. Current gauge readings at ambient temp 86 degrees, not running (L 115 H 120), at idle (L 32 H 200) and at 2K RPM the compressor cycles off at (L 60 H 218) and then cycles back on gain when the pressure drops. Suspecting I may have a restriction. I replaced the orifice tube, that is about all I can think of.

TRB on Sun October 02, 2011 9:43 PM

So you replaced the compressor 5 years ago and just the hose recently. This groaning noise only showed up after the hose replacement and additional 3 ounces of oil?

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BajaScout on Mon October 03, 2011 4:38 AM

The noise appeared after replacing the hose and orifice tube and adding 1 can of R134. I added the second can and 3 ounces of oil but the noise did not go away. Is it possible I am just low on R134A still?

TRB on Mon October 03, 2011 5:05 PM

This vehicle lists at 32 ounces of refrigerant and 8 ounces of oil. Having the proper amounts of both are important to the systems performance.

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