Hi,

Intermittently, I've got a really loud grinding noise when the climate control is turned on. Turning it off immediately silences it.

It happened a couple of times just after I bought the car about a year ago, but it didn't come back until the other day and now it's happened three times in a week. Turning off the CC for a while and turning it back on seems to "fix" it for a while at least.

Any ideas what this could be and what I can do to fix it?

 

My first thought is always the compressor. When they are failing, they begin to make noises ranging from cement mixer rumbles to full-blown screaming. Put the front end up on ramps and listen to your compressor while laying underneath it. A mechanic's stethoscope would be handy in this situation as well....

 

As an easier test, next time it happens I'll turn the heat up and turn the AC off. If that stops it, it's AC related, if it doesn't, I think that rules out the compressor?

 

Not necessarily. Your compressor can run anytime the HVAC system is on....

 

Ah, why are things never easy?

If it is the compressor, would a mechanic be able to tell it's on its way out even if it's not making a racket?

As it's intermittent I won't be able to listen to it when I want to.

 

They could put pressure gauges on it, many times when these are going the pressures will be off.


Dave

 

While not common, it might be the auxillary coolant pump, an electric motor pump that circulates coolant through the heater core. I had a loud intermittent grinding noise that I actually believed was the A/C compressor, but finally one day while listening for the noise with my head under the hood I heard it and confirmed it was not coming from the compressor. After months of hearing the noise, I think it became somewhat more frequent, and I found that powering off the hvac system and back on sometimes could force the noise. This is how I was able to pinpoint it. The pump was replaced, and I never heard it again. The bad news is that the pump isn't cheap, and the labor is time intensive. I am very mechanical, but decided to let the dealer do this one. The pump sits above the transmission bell housing area behind the Throttle Body area. It requires removal of the TB, and even then it is not easy to get to. In addition, I had the octopus hose assy. replaced at the same time, as the pump is connected to it, and it wasn't in great shape. With the new pump, hose assy. and labor, my total cost was about $1200.