Whenever I have the AC on (or this time of the year the defroster) my car makes a loud rattling/grumbling noise....is this the bearings in the AC pump? Though I've owned my car for 207K I've never had to mess with the AC. What's the fix? Is it cheaper just to source a used pump and have it put in?

umm...anybody? bump

Are you sure you aren't complaining about the heater fan? They will either have a maple key or debris fall through the air intake and get lodged where the fan can actually hit the culprit, and make a noise that changes with the fan speed setting. Sometimes the fan motor bearings will go and you get a squeal or rumbling sound. Then again, the bearings in your AC compressor may be gone, giving you a squeal or rumble. Unfortunately, unless you are handy, all of these problems take time to correct, and if its the AC compressor, money as well. A used or rebuilt AC pump may be the cheapest way to go, if its needed.

I just had this happen to me. My system is R12 and it is getting very hard to get R12 to put in it. I'm sure that the compressor is blown on mine, so I'm going to convert the system to R134 with a lot of new parts. . . Talking on the order of $300 to $400 here. . .

 

Just a new pump should be less however.

Pump or maybe just the clutch on it.

Pump or maybe just the clutch on it.

When mine went it locked up the belt (belt gave off a squeal like a banshee, and I could smell it burning), then gave off a sound like piston slap from hell (once the belt started moving again). . . . I'm pretty sure it is the pump in my case. . .

 

No way it is the heater fan. Too loud, wrong kind of sound, and it was coming from the wrong place (engine compartment instead of the cabin)

Easy to pinpoint noise with a length of rubber hose to the ear, then zero in on it.

 

I have an old stethoscope I use.

Thanks for the replys....definitely not fan....I've dealt with that problem before. Also it ONLY makes the sound when I use the A/C or defrost and there is a perceptible lug on the motor. So, I'm thinking pump or clutch (clutch is something I haven't considered). Advice on how to proceed?

and run it for just a few minutes to see if that is it. While it is off roll the pump over by hand and look for play and noise.