I've had this for a while now and no one I talk to can definitively say what the issue is. Whenever I use my climate control (A/C or heat) I get a very loud rattling noise, but only when the vehicle is in Drive. It's loud enough to turn heads, and it's honestly kind of embarrassing in traffic or going through the base gates. The air blows cold or hot, as it is supposed to. Any ideas?

 

Where's it coming from? In the cab, or under the hood? Will it do it while you are stopped, with your foot on the brake?

 

Sounds like it is coming from under the hood somewhere. I was thinking condenser fan at first, but I don't know what being in Drive would have to do with that. Doesn't matter if I'm stopped or moving, throttle or brake. It's not rotational or throttle related (like the clutch fan would be). So, in my limited mechanical knowledge, I'm stumped...

 

Have someone you TRUST stand on the brake, while you look around for what's buzzin'. It *might* be because the engine torques over a bit when you put it in gear...... Maybe.....

 

Hmmm... I'll try that. I don't think we've told the teenager exactly how much we're insured for, so I may be safe if I have her do it.

Thanks for the advice!

 

May wanna set the ebrake as well...... Just incase she already knows........

 

I still can't figure out what exactly is generating the noise.

I guess on the positive side, I didn't get run over...

 

That's always a plus. Was she tempted?

Are you sure the noise is coming from under the hood?

 

No, I'm really not. I only really hear it myself when the windows are down, so I don't think it's coming from under dash, but I could be wrong. It doesn't seem to be any louder, quieter, or different in any way with hood open/closed.

What's the order of systems that have to operate for the climate control to either heat or cool? Time to break out my Chilton's and see if I can't troubleshoot it one step in the system at a time.

 

The only change when running a/c vs. heat, is the compressor is running. That puts a bit more of a load on the engine, and the PCM should compensate, by bumping idle a bit. I don't know how all the vents work on the third gens..... if there is an electric controller in there somewhere, it *might* do something when you engage A/C, but, I doubt it.

I think what I would do, is touch EVERYTHING (that isn't moving) related to the a/c system under the hood while it is making the noise. See if anything obvious presents itself.