Vintage Air Grinding Sound

[houstonshark]

Over the past couple weeks, I have noticed a grinding sound at certain RPM's when the AC is on, at certain RPM's. If I back off the gas a little or turn off the AC, the sound goes away. I assume this has something to do with the AC compressor, but I know very little about how these work.

Any input or troubleshooting suggestions would be appreciated!

[Donaldo]

Had a Chevy truck make sounds like that, the a/c clutch was slipping/grinding on the compressor shaft when initiated. It only happens here on the hottest days of the year....

[dwcsr]

Originally Posted by houstonshark

Over the past couple weeks, I have noticed a grinding sound at certain RPM's when the AC is on, at certain RPM's. If I back off the gas a little or turn off the AC, the sound goes away. I assume this has something to do with the AC compressor, but I know very little about how these work.

Any input or troubleshooting suggestions would be appreciated!

Don't rule out your water pump and any idler pulleys

[houstonshark]

What's odd is that it actually sounds like it is coming from the under dash unit. I can't imagine why it would be RPM or throttle dependent though.

[dwcsr]

if its the compressor it will transmit the noise into the inside unit through the Freon,

[roger55]

Originally Posted by houstonshark

What's odd is that it actually sounds like it is coming from the under dash unit. I can't imagine why it would be RPM or throttle dependent though.

One of my VA installs does it too. It's compressor drone and the sound is transmitted to the under dash unit. I just ignore it since it doesn't affect anything.

Sometimes the factory put mufflers on the pipe coming off the compressor to suppress the noise.

[OrrieG]

I knew those new fangled drones would cause problems....