Heater squeal - control box?

steely · 01-01-2010, 11:18 AM

Hi guys - just another curiosity question. I saw the posts on taking care of the footwell blower squeal, but has anyone ever heard the noise made when you first turn on the heat?

It's like the fweep bird got in my car, and I think it's related to the servo motor in the heater control console. I scanned Bentley, but it just shows tear down. My questions are: Is it normal, or can it be fixed?; Is the noise source the servo, control linkage, or the heater boxes? (I never stopped to listen/get my ear down there); and, is it because the control potentiometer is dirty causing constant position correction?

I get heat, but when I first turn it on, you get a long "waaa" sound, followed by a couple of fweeps :-) or chirps lasting a minute or so like it was correcting it's flap position - kind of funny almost. Or is all of this normal.

Thanks!

steely · 01-01-2010, 06:23 PM

I don't think the sound is coming from there (feet), certainly not the drivers side anyway. Besides, wouldn't they squeal for the entire time they're on (of say a 35 minute drive)? This noise only occurs when you adjust the heat dial on the control (console), not the fan speed on the dash. Or do I misunderstand? Thanks

on edit: I have the batt disconnected for some other winter projects, so I can't test anything right now.

javadog · 01-02-2010, 03:52 AM

Quote:

Originally Posted by steely

the fan speed on the dash.....

....has nothing to do with the heater...

JR

wdfifteen · wdfifteen's Garage

Quote:

Originally Posted by steely

I don't think the sound is coming from there (feet), certainly not the drivers side anyway. Besides, wouldn't they squeal for the entire time they're on (of say a 35 minute drive)? This noise only occurs when you adjust the heat dial on the control (console), not the fan speed on the dash. Or do I misunderstand? Thanks

on edit: I have the batt disconnected for some other winter projects, so I can't test anything right now.

The dash lever doesn't control the footwell fans. The knob between the seats does. Sounds like you've got bad bearings in one of the fans.

tcar · 01-02-2010, 10:58 AM

Could it be coming from the rear of the car? Right behind the back seats?

Could be the main blower fan bearing going South.

Goth · 01-02-2010, 11:33 AM

Quote:

I get heat, but when I first turn it on, you get a long "waaa" sound, followed by a couple of fweeps :-) or chirps lasting a minute or so like it was correcting it's flap position - kind of funny almost. Or is all of this normal.

I have the auto heat option (not all have this) and it does the same thing as yours. It sounds like a hamster running in one of those wire wheels

. It was very loud the first couple of times I used it, but has since become a lot quieter with use. It also does a lot of adjusting when you are on and off the gas as it tries to compensate for the big temp swings in the heat exchangers.

I think your right on with your assumptions... Since mine got quieter; I have not bothered to look into it further. I know this is not a fix, but at least you know your not alone (LOL).

FYI: I have already oiled all the fan motors which BTW use to make a different squeaky sound.

steely · 06:04 PM

Thanks Goth - I was about to post that it still wasn't the footwell blowers. Auto heat - aha!

The car is a little disabled right now, but to check my sanity I connected the batt and turned on the heat (center console knob) and the drone noise is in fact the servo, or at least coming from heater console (under the knob) - but I could not repeat the secondary noise - maybe 'cause the engine was off(?) / no heat to be had of course.

Thanks everyone for the input!

on edit: looks like we have a fix!:
Auto heat servo unit.