Chirping Noise when AC/Heat On

[J29382]

Hi there, 

hoping someone can give some advice and insight. I have a 1999 chev 1500, 5.3L.

 

Every time the heat is turned on, or the air conditioning is turned on, there’s an intermittent chirping noise coming from under the hood. I don’t believe it to be the blower motor because I don’t hear the chirp clearly/at all from inside the cab unless I’m parked. However I can hear it clearly when the window/windows are rolled down.

 

I had thought that maybe the AC clutch/compressor is going out, but I don’t understand why the chirp would occur even with just the heat running. I made sure that the AC button is off when I run the heat to verify that the chirp happens when either cold or hot air is coming through the vents.

 

Perhaps is a pulley bearing, bad belt, or A/C tensioner? Any help is greatly appreciated.

 

Thanks,

- J

[richard wysong]

Look to see if the compressor is running with the heat on, it does run on the defrost setting heat or a/c to dehumidify. The compressor has its own belt and tensioner pulley so my guess is the tensioner pulley is on its way out but it could be just the belt

[J29382]

14 hours ago, richard wysong said:

Look to see if the compressor is running with the heat on, it does run on the defrost setting heat or a/c to dehumidify. The compressor has its own belt and tensioner pulley so my guess is the tensioner pulley is on its way out but it could be just the belt

Thanks. It is the AC clutch that makes the chirp sound when it starts spinning/is engaged. Is there any way I can just unplug it for the winter to keep the AC clutch from running until I can get to it in the spring time?

[richard wysong]

unplugging the pressure switch on the suction line should shut it off, easier to get to than the compressor wires.