Hi there
First of all, thank you all for the great site. I recently discovered it and registered.

I bought a 2004 Explorer V8 in January, and it has run perfectly until recently. At around 4000 miles I noticed that there was a squeak or chirp sound coming from under the hood. I thought it might have been the serp belt, but I had my doubts. The chirp happens when the AC is on. When on highway at ~2000RPM it happens every 12 seconds like clockwork.

The dealer replaced the serp belt today. I asked if it was all fixed, and the mechanic said, "yes." Anyway, I got on the highway and there again was the chirp. I went back and talked to the mech again. He looked at it, heard it, and said it was the AC compressor clutch. Then he basically implied that it was normal and wanted to sweep it under the rug. Come on . He seemed like a nice guy, so I took it lightly and told him that I wanted it fixed. He put a new compressor clutch on order.

If it weren't so loud I probably wouldn't care, but a 33K $ truck shouldn't do this. I've never heard a squeak or chirp when a compressor cuts on on any car or truck. I hope this is not another misdiagnosis. Anyone have any ideas? How common is this? Is it "normal?"

Sorry for the longwinded message. I guess I am annoyed that the dealer couldn't get it fixed the first or second time.

 

I have a problem similar to that on my Explorer, when around 2000 RPMs (usually accelerating) and I press the A/C button I hear a short grind/clunk sound and the car lags a bit. I would hear it every once in a while but didnt connect it with the A/C until today. Ill bring it into the dealer this weekend and see what they diagnose.

its a 2003 with the 4.6

 

I do not know if this makes any difference, but I do not have the auxiliary climate control. There is no noticable lag or clunk on mine, just a loud chirp. Though it also makes the chirp on lower rpms, and occasionally a muted chirp on idle.

Let me know what you find.

 

hrdux,
Have the refrigerant level checked. It sounds like the compressor cutting in and out. Some make more noise then others. The frequency of the chirp sounds like low 134A level.