Mavel

Hello!
I recently realized that when I drove with cab up and no stereo on, there was a hissing/whistling sound from the ventilation nozzles from the dashboard. If I have the temperature control on the AC on 18 - 23 degress, the sound is there and the speed control on 0 -1 ,otherwise it disappears. Does anyone know what can be the fault?

What is there to do?

Grateful for help!

RallyDogRacing

Man I hope you find it because mine does the almost identical thing. I thought for the longest time it was an airleak in the engine side. It's perhaps and airleak/vaccuum leak for the flapper motors or something but I haven't pursued it.

jimq

You sure you are not hearing the little fan on the CCU?

rbatt

Mine does this too. I've noticed that the noise seems to change or lessen when I steer to the right (rhd). It's quite annoying because I keep thinking that something is wrong.
The whirring noise on my car seems to come from an area to the right of the seering wheel (remember rhd) near the key/ignition. Any Ideas?

Robert Batt
1992 C2

John Boggiano

Mine does it if both sliders are closed (to the left). If I open one, just a little, it disappears.

Heirsh

I have a whistling noise as well. It oscillates very regularly up and down in level. It does so based on the temperature setting. If I leave the temperature setting on its lowest value it does not do this. I've assumed it was the system adjusting something to keep the right temperature air. Kind of just oscillating around the target instead of settling into it nicely as I would guess it should. It sounds like a fan to me, but that is only a guess. If it is a fan it may need some work (bushings, cleaning), but I havent undertaken the project yet.

doug751

My guess; actually my mechanic's guess....
The foam rubber seals in your HVAC system are breaking down. They tear and flap in the wind. In my case, there are some rubber seals near the center went that are going to be replaced when my center vent is replaced this week. I will report on the results.

Another possibility...
The squirrel cage fan for your AC system spins on a cheap spindle. Clean and lube that spindle and all will be well for a few years. (That sound is more like a criket chirpping at low RPMS and screeching at high)

RallyDogRacing

I've been paying attention to the whistling in my particular car. Once the whistling starts, I can make it go away by changing the desired cabin temp **** by 3 or 4 deg C either cooler or warmer. Once the cabin gets to that temp, the whistling starts up again. Wierd... It's independant of the fan-speed in my particular app.

Marc Shaw

Could it be the little fan on the back of the CCU?

Marc

RallyDogRacing

I suppose it could. I haven't figured out how to go about removing the CCU (the head unit I presume we're talking about) from the dashboard to see if I can find the bugger.

Since I'm now in heightened fully-whistle-awareness mode (code: orange) - I also occasionally hear another one from the rear of the car too. Alas I've decided to pretend it's not really there until I get this front one resolved.

So going back to other people comments, could it simply be the over-time degredation of the foam seals on the flap-doors of the HVAC system. When trying to mix outside and inside air for that "just-so" setting of the desired-temp ****; perhaps I am getting bleed through elsewhere.

Or I could just be nutz anyway.

jimq

Get a louder exhaust or just turn up the radio. Works for me every time to drown out worrysome sounds.

bhensarl

Mine only whistles when the A/C is on. If I turn off the A/C, the whistle disappears. I've pulled the CCU fan off and lubed that baby, so I know it's not that (it's a different sort of sound). That job is very easy, in fact, RDR. Here's how to do it:
How to fix a squeaky CCU fan DIY
Brian