intermittent high pitched moan from AC
Thread Starter
TECH Fanatic
Joined: Nov 2001
Posts: 1,695
Likes: 9
From: Raleigh, NC
Pontiac Montanna...? Just wondering if anyone here owned one or if there is a message board out there for them?
When his AC is on it makes an intermittent high pitched moan.??
Thanks,
-Nick
When his AC is on it makes an intermittent high pitched moan.??
Thanks,
-Nick
We have one, a '99. Wife drives it. She loves it. I think it's a great van too. Decent acceleration, rides nice, minimal trouble (watch that 3.4 for an intake manifold leak 
I changed the gasket - 3rd time since we've owned the van, but my first time to do it myself - a few weeks ago).
Can't say I've ever heard moans from the A/C system though. Coming from inside or outside the cabin? You've got the squirrel cage fan inside, or the compressor outside. Those are really the only 2 parts of an A/C system that move.
I changed the gasket - 3rd time since we've owned the van, but my first time to do it myself - a few weeks ago).Can't say I've ever heard moans from the A/C system though. Coming from inside or outside the cabin? You've got the squirrel cage fan inside, or the compressor outside. Those are really the only 2 parts of an A/C system that move.
TECH Veteran
Joined: Dec 2004
Posts: 4,012
Likes: 1
From: Beaumont, TX
moaning noise when the A/C clutch is engaged:
Connect an R-134a manifold gage set to the low and high side service ports on the vehicle refrigerant system.
Increase and maintain the engine speed at 2000 RPM, in PARK.
Engage the A/C clutch.
Check the low and high side refrigerant pressures.
Compare the pressure readings to those listed in the System Performance Chart. (Sunday 8/21 in Blacksburg, VA, it'll be 60% humidity and about 90°F at 2pm. Pressure readings for that temperature/humidity should be 310 kPa/45 psi for low side, 2482 kPa/360 psi for high side.)
Are the high and low side refrigerant pressures within the normal specified limits?
If yes (they are near the normal numbers):
Inspect the A/C compressor mounting, idler pulley, and tensioner / tensioner pulley for concerns using a stethoscope. Replace any of these components that are loose, damaged, or excessively worn. If none of them are, a component could be grounding out.
If no (they are not near the normal numbers):
Recover the refrigerant, evacuate and charge the refrigerant system to specifications.
air rush/whistle noise:
- temperature valve seals could need to be repaired or replaced
- obstructions or foreign materials could need to be removed from the air ducts
- defroster valve seals could need to be repaired or replaced
Connect an R-134a manifold gage set to the low and high side service ports on the vehicle refrigerant system.
Increase and maintain the engine speed at 2000 RPM, in PARK.
Engage the A/C clutch.
Check the low and high side refrigerant pressures.
Compare the pressure readings to those listed in the System Performance Chart. (Sunday 8/21 in Blacksburg, VA, it'll be 60% humidity and about 90°F at 2pm. Pressure readings for that temperature/humidity should be 310 kPa/45 psi for low side, 2482 kPa/360 psi for high side.)
Are the high and low side refrigerant pressures within the normal specified limits?
If yes (they are near the normal numbers):
Inspect the A/C compressor mounting, idler pulley, and tensioner / tensioner pulley for concerns using a stethoscope. Replace any of these components that are loose, damaged, or excessively worn. If none of them are, a component could be grounding out.
If no (they are not near the normal numbers):
Recover the refrigerant, evacuate and charge the refrigerant system to specifications.
air rush/whistle noise:
- temperature valve seals could need to be repaired or replaced
- obstructions or foreign materials could need to be removed from the air ducts
- defroster valve seals could need to be repaired or replaced
