Help - Intermittent knocking noise under engine,

[ntmepath]

So the AC went out abruptly today on the way home from work. once i got home i noticed an intermittent knocking noise at idle. it sounds like its coming from underneath the engine.

https://youtu.be/vqeiqD7Z1Kk

[smj999smj]

Couple of things you can try. Use a mechanic's stethoscope to try and pinpoint better where the noise is coming from. Remove the serpentine belt to make sure it's coming from the engine and not one of the drive components. You probably already check the oil level. A water pump, which is timing chain driven, with a bad bearing, could make that noise. Hopefully, it's not something internally in the engine. My thinking is the knocking triggered the knock sensor to signal the ECM, which, in response, cut the power to the A/C clutch, which is why your A/C system stopped working.

[ntmepath]

Dealer could not find any issue and the noise has never repeated. The AC compressor clutch did burn up so getting a new system put in tomorrow. It's disappointing to have these issues at only 118000 miles.

[smj999smj]

I had the A/C compressor clutch go out on my 2006 when it's coil failed. I was able to find a replacement clutch for around $110 and was able to replace it with just removing the fan shroud out of the way. I didn't have to remove the compressor nor do anything with the refrigerant.