My recently revived '85 is making a very strange noise when I turn on the environment controls. It's sort of a high pitched chirping that comes out of the pod for about 15 seconds then stops.

Is this bad? Any ideas on what needs replacing?

 

Usually that is from the inner temp sensor motor (the one on the dash) It will get more annoying as time goes by.

 

I had a damn bird chirping away on my last 993 that just drove me insane. Found it in the passenger side cabin fan motor under the front cowl. A few drops of Break Free quiet it down.

 

A vacuum actuator with a bladder starting to go bad can make high pitch chirp or warble sounds like a whoopie cushion.

 

Our 88 had that. It is the temperature-control motor that runs the mixing flaps, left side of the console. Disassemble and lightly oil the motor shaft.
The definitive test is to change the temp slider, chirping will start or stop.

 

My guess it is the blower mower bearing. Next time is crops up, adjust the fan speed and see if the the noise changes or goes away. Mine started occasionally chirping on low... and eventually started to chirp all the time. Replaced the motor with a used one a few years back and all was good until recently... now it's chirping again. I believe Roger has a fix that either replaces the motor or bearing with something new. That is the route I would go.

 

I agree with auzivision: are you sure it isn't the HVAC motor itself? Mine chirped exactly like that, and it sounded like it came from the dash, but in reality it was under the hood.

If it is the HVAC motor, the bad news is that you have to remove the hood, which in my novice hands is a pain in the a**.

The good news is that it will give you the opportunity to clean out the leaves, acorns, etc. that will have accumulated in there.



You should also clean the evaporator so that your air smells very fresh (and you get more of it.) While you are in there (if it is in fact the HVAC motor) you should change the "resistor pack," which often fails.

The other good news is that you can buy a replacement HVAC motor from Roger, without having to buy the entire unit. You undo five or six clips, pull out the old squeaky motor, and put the new fresh motor in.

 

Jim & Sue write "The definitive test is to change the temp slider, chirping will start or stop."

Bingo. Moving the slider to "off" makes the noise go away.

Scott writes: "The good news is that it will give you the opportunity to clean out the leaves, acorns, etc. that will have accumulated in there."

Kurt writes: "Mine started occasionally chirping on low... "


Laughing. Really! Not out loud but laughing anyway.

When I did the intake refresh on this car last summer I cleaned out acorns! Honestly!

Thanks for the advice everyone. This list is invaluable. I have saved thousands of dollars here. Best money I EVER spent

Best Regards,

 

BTW; Scott? You ever get up to Laguna Seca? I'm on hold for the driving school at the end of November. If you're going I'd be happy to let you listen to these squirrels and give me an unvarnished opinion

 

Oh, and for Mark, thanks too. Whoopie Cushion is close also..

 

Joe, I have to ask; what did you put on that dog?

 

Scott,

talk to Roger. He has a direct replacement electric motor available for the fresh air fan. The lower bushing on the motor goes bad over time due to the higher centrifugal force of the fan. Once the bearing is worn, it´s time for a new motor. Porsche only sells the complete housing with motor and it will cost you an arm and leg...

https://rennlist.com/forums/928-foru...placement.html

 

Scott, the husky (Dutchess) just got back from chasing bullfrogs in a sump hole.

 

We had this also, in our '90GT. It was more of a "squeal" than a "chirp", but as Kurt pointed out, this noise changes when you change the fan-speed switch and not the temperature-slider.

We fit Roger's replacement motor, perfect fit once the blower housing is out and disassembled (mark the hood hinges for reassembly). The new motor is beefier which is great for airflow, and is a very nice update. But the additional current does require upgrading a couple of 1.5mm wires in the harness in the cowl area (thanks to Greg Brown for that tip, the finger-test for hot wires trumps fancy meters).

And the new motor does add a bit of load to the resistor pack, but also boosts the airflow which dissipates the heat. So +1 on cleaning the evaporator, that will also boost airflow and keep the resistor pack from overheating and failing.

Cheers, Jim