My wife called yesterday to say that the engine was knocking really bad, stopped and then started again a few minutes later. She also said that when she ran the A/C that there was a "whooshing" sound.

When I got home last night I checked it out with a stick of PVC and the noise seemed to be coming from the front of the passenger side valve cover. I thought maybe the cam phaser, but I understand that it should be cold to check if it's making noise.

This morning I started it up to check and the knock was still there. My wife mentioned the a/c again, so I turned on the a/c and the knock stopped. Turn the a/c off...knock starts. When the a/c clutch engages, the knock stops. Then my wife remembered that she had turned on the a/c, and then off again on the way home. Makes sense.

What, in the compressor, would make this noise? Or is there something else I'm missing? I don't want to spend money on a compressor if that's not it. The "whooshing" sound too. Haven't figured that one out either. BTW, the a/c blows cold and seems to cycle normally.

 

Disconnect/remove the belt and see if the noise is gone. If you can pinpoint it to the compressor, which they do make god awful noises when they go bad, they have bearings, clutches and other parts that fail... then it needs replaced.

 

Check the mounting bolts on the compressor, had one once that had a knocking noise and the bolts were loose!

 

Thanks for the replies. I'll check those things and get back.