Odd heater fan behaviour

[andyt11]

I have two odd things going on with the heater fans in my 88 911.

The first is that when the car is cold and the fans run for the first time, I get loud buzzing / reed whistle sound from behind the dash! Sounds like one of those things kids blow on at birthday parties and a reed makes a loud noise as it unrolls.

The other problem is that the fans don't always run. Especially early on in a run. They only run when the engine speed is over say 2k. So when I stop at a light the heater fans turn off. This happens at all fan speeds.

The buzzing / reed whisle sound also happens when you turn on something that draws a lot of current, like the heater rear window. The fans can be running fine but when you turn on the heated rear window the buzzing starts.

All the problems reduce in severity and frequency as the car warms up and I guess the fans warm up.

Any thoughts? I suspect more than one issue, but one of the issues is current related for sure.

[andyt11]

No one got any ideas? That'll be a first for this forum....

[timmy2]

Remove and clean all your fuses and holders in the front and rear fuse panels and see if it goes away.

[scarceller]

Remove the fans in the kick panels and inspect them. The squirrel cages on these fans often slide down the shaft and rub against the housing. Take both left and right hand side fans out and inspect them. While at it power them up on the bench via 12vdc power.

[db_cooper]

If your footwell blower(s) are squealing..they are going out. You might get some miles on them with lube.

Scar is right..the squirrel cages start rubbing..hence the noise. Its only a matter of time and they start smoking dramatically.

Shop around for new footwell blowers..found mine on the Bay..brand new in box old stock..OEM Porsche $100. About $250 elsewhere..or $440 from Porsche.

Those footwell motor squirrel cages start dragging/brush assemblies get hot then the plastic melts, smokes and smells very bad.

[db_cooper]

Remove the kick panels on each side..two phillips head screws and unplug your footwell blowers. Best test for noisy footwell blowers.

See if your noises subside and heat operates then let us know the results.

If your squealing goes away..test one side then the other by plugging them back in..see if both or one footwell blower is bad.

There is a temp/vacuum switch on the 3.2 breather that will start making noises about this time of year. Its in the right side rear of the car near the oil filler. They can startle you too.

[SLR]

Yep I have the same thing with the fan in the back. It makes a hell racket, some times. I pulled it apart and lubed it with a hight temp wheel bearing grease, it worked fine for a bit . I will lub it again in the next day or two, but I think it is on it's way out.

[wwest]

Originally Posted by SLR

Yep I have the same thing with the fan in the back. It makes a hell racket, some times. I pulled it apart and lubed it with a hight temp wheel bearing grease, it worked fine for a bit . I will lub it again in the next day or two, but I think it is on it's way out.

30 weight will work much better, soak the brass bushing/bearing and the cotton wadding.

[86 911 Targa]

This predictable issue surfaces every winter.

We very rarely use the heat on our '86, but have tried, to no avail,
all of the posted "fixes", to eradicate the low speed squeal
on one of our foot well blower motors.

eBay does have some listings for used complete assemblies,
but that's another roll of the dice.

Also, sent a pm to Wayne in March of this year,
requesting the "motor only" as a stock item,
but no joy yet.

Perhaps some of our members can send a follow-up email to Wayne.

Gerry

[andyt11]

Thanks all. Seems like the squeal is found. Does this explain the eratic operation too? I'm thinking it might be related. I'll pull those fans out in the next little while and run on the bench. Thanks for the pointer.