Fresh Air Blower Squeal Fix

[JeffWeb]

I didn't find a post on this exact issue so thought I'd start one .... the fresh air blower on my '85 911 worked OK except it would squeal loudly at higher revolutions. I removed the unit, split the housing, pulled the motor/fan assembly out, and didn't see any charred components or anything unusual.

It was easy to reproduce the noise while holding the motor in one hand and spinning the fan with the other. Over 30 years dust had accumulated on the inside of the fan near the motor shaft causing very slight friction between the rotating fan body and stationary motor housing.

The fix is to drip a little light weight oil into the hole shown by the red arrow, flip the fan over, work the oil around, and repeat once or twice until the squeal stops. The fan now spins more freely and sounds like new after installation.

As a bonus my fresh air now has the refreshing 3-in-one oil fragrance. Hope that helps someone.

[Kidasters]

Those little rings are tough to get back on, aren't they.

[Jayt]

My blower makes the same noise. How do you access the blower? Do you have to split the case to access the lubrication hole?

[JeffWeb]

The blower is located directly under the fresh air intake at the back of the frunk. It's behind the paperboard panel. Fairly easy to remove. You do have to split the case to expose back of the fan and lube hole. Getting the case back together is the hard part with those round spring clips that Kidasters mentioned. Might not be a bad idea to get a new sealing ring (901-571-922-01) since old ones fall apart.

[Reiver]

Very timely, I was going to investigate that very issue. Mine sounds like an Elk mating call.

[rick-l]

why is a compass rose on the back of the blower?

[Reiver]

Originally Posted by rick-l

why is a compass rose on the back of the blower?

Yeah, didn't notice until you mentioned it.

[gptom]

balancing marks

[sugarwood]

Originally Posted by JeffWeb

As a bonus my fresh air now has the refreshing 3-in-one oil fragrance.

I love the smell of TriFlow in the morning !

[Jayt]

Your post gave me the boost I needed to do this fix. The results are impressive! After 36 years the internal surfaces of the blower were filthy and everything needed a good cleaning. In addition to the blower shaft, I also lubed up the pivot points for the control flaps. No more squeal from the fan and as an added benefit, the heater/defrost controls now work smoothly and almost make sense. Unlike the previous anemic airflow, the blower now pushes lots of air. I am almost looking forward to the next time I need to demist the windshield. I should have done this years ago. Thanks for posting this easy fix.

[sugarwood]

I never was able to remove the shaft and truly dismantle the motor. All I ever could do was to loosen the squirrel cage, and lube the felt washer, which seemed absolutely pointless. How are you supposed to remove the shaft from the motor ??

[porsche930dude]

Good advice. If youre blower shows any signs of binding or squeeling at all fix it immediately! The brushes melt all the time in these motors because of this and then youre motor is toast

[sugarwood]

If the cage binds, the 10a fuse will blow.

[porsche930dude]

tell that to my blower. and the used one i bought to replace it that was also melted. There was a thread on this in the past and many people had melted brushes. I believe someone found a cheap replacement blower from a toyota or something that fits the housing well. I was able to get mine going again with parts from both melted units

[crashtest22]

FWIW I had this squealing issue and started searching the forum on how to get the fan off the motor to replace the motor. I could not get it off so I used electrical contact cleaner and sprayed the heck out of the motor till it was coming out the other side clean. Then lubed the top and bottom and tested.
Squeal is gone for now. The replacement fan is on factory backorder from what I can tell from Bher so this will hold till it does it again if it does.

[911T1969]

When the squealing starts, the motor is shot. Lubing is a temp fix. I got an exact replacement Bosch motor for $89. The plastic fan is just friction fit onto the motor shaft. Pull from the the fan body not the blades.

[dan88911]

Thanks for posting JebWebb.
Here is another old thread on this subject.
With some more good photos of the fan @ post#93
Fresh air blower controls

[sugarwood]

Can you post what Bosch motor was a direct replacement?

[911T1969]

Pelican has them. I used Part number 0-130-007-002-M14 on my '69. Make sure that would fit your '86
I've seen them other places for as low as $75.98
Carefully use a punch to tap the shaft out of the plastic fan.

[bweiss1]

Does anyone know how to obtain either new "flaps" that are in the blower housing, or new rubber for these flaps? I have attached pics so you can see what i am talking about. Even a genius idea from one of you engineers of what material to cut a disc to shape. Mine are disintegrating.

Many thanks and thanks for the great write up. Worked like a charm!