Pierpressure

I finally figure out why my 928 had no temperature control with heat or AC.. It turned out to be a bad outside air sensor which I replaced with a used unit from 928 International. That did the trick but now there is a noise coming from the dash that sounds like a fan squeal but I do not think it is the blower motor. It goes away when I turn the HVAC to off so it is related.

Is there another motor related to the system that would cause the noise?

davek9

Is it the inside Air Sensor on the dash (there is a small fan inside the unit that pulls air in)?

Kevin in Atlanta

Vacuum pod has ruptured. Dwayne has a write up on replacing them.

joejoe

more than likely it is the interior sensor motor. Mine sounds like a squirrel chirping when cold, goes away when warmed up.

syoo8

When you turn the HVAC to off and the noise stops-- why do you come to the conclusion that it is not the blower motor? It is the only thing that stops when you turn the HVAC to off.

dfrhodes

It may be the regulator (mixer) motor that sits below the pod, above the accelerator pedal.

Does it only squeal when you adjust the temp slider? It is controlled by the sensor loop which explains why it has started working now that you have an outside sensor connected.

its pretty easy to remove and take apart. there are some plastic gears inside that may need some grease

Pierpressure

The noise is coming from the pod area and it is my understanding that the blower motor is on the passenger side. Also, the noise does not change when I adjust the blower speed. It is intermittent even with the temperature in a set position as well as the blower speed.

Koenig-Specials 928

+1
Mine squeals when cold and goes away when warm

WallyP

First thing to try is to disconnect the small vacuum line from the black/blue check valve at the brake booster, start the engine and the HVAC - if the noise is gone, it is probably a vacuum leak. Hook the line back up - if the noise reappears, it is virtually certain to be a vacuum leak.

If it isn't a vacuum leak, the small sensor fan is a likely suspect.

danglerb

My first dealer repair on my first 928 almost 30 years ago. Squeal in the dash was spoiling an otherwise quiet ride, so I take it in to the dealer and say fix it. $179 for the motor, and $400 labor to R&R the dash and replace it.

Hindsight maybe a long skinny tube and a shot of something like PB Blaster (not WD40 as it doesn't lube very long) down the sensor tube.

There is a plastic fascia on the dash, an air temp sensor, and a small 1" or so diameter duct down to a fan motor that draws air through the sensor. The idea would be small tube past the sensor so the lube sprays on the motor. No idea where it might drip.

outbackgeorgia

Most everyone's guessng....What Dan said, small motor in temp sensor tube, needs lube.
Dave

Pierpressure

Sounds like it is worth a try. I will give it a shot when I get back into town next week. At Barrett Jackson watching fools spend $200k for a 1970 Chevelle.

WallyP

"The noise is coming from the pod area..."

Reread Post #9. Takes five minutes, costs nothing.

Pierpressure

Had a chance to pull the vacuum line today and the noise is still there. Anyone know how hard it is the change the temperature sensor motor and is there a DIY?

joejoe

Removal of center consul is needed. It is not terribly difficult, but time consuming. While in there take a real good look at the vacuum pots behind consul. Heck, if you are there just bite the bullet and change them. If you don't you can bet one or more will fail soon.

Remove passenger tray and glove box, sides to consul, and cassette storage. remove center vent (2 screws there). This is a start, I am sure there is a write up here (although search rarely works well for me)