Cabrio Rear defroster fan motor and housing

Hi,

In case you have ever wondered what a cabrio's fan motor and housing look like, here your go. This is the fan from my 325i 1989 car. :-)

















Now you knnow what it looks like!

Mine is making a noise. Bob is helping me wih this a bit. :-)

I removed the motor from the housing. This is about as far as I can proceed with out being damaging the part.

Cheers, Kelly

Kelly,
The "spare" fan I have is exactly like yours except dusty from being stored with a bunch of other parts for quite a while. Also on mine two of the three motor support legs of the housing are cracked, probably from being in a box with some other parts. I can reinforce with metal and epoxy to make it serviceable. The motor runs smoothly with power applied and the fan is undamaged. It could also be removed for use in your housing if preferred. Getting sockets out of the connector is a challenge that can be overcome with splices of the wire if a proper tool is not available.

I would not attempt to disassemble the motor and fan. The fan appears to be pressed into place or bonded in some way. The crimped washer retainer you have noted on the other end of the motor would be damaged by removal for sure. Does the motor shaft have any radial free play or looseness? Does it spin freely or is it noisy?

Bob

Bob in Lake Havasu

Hi Bob,

Thanks for asking good questions.

I don't think there is any radial play between the fan's central shaft and the motor. If I wrap one hand around the motor's outer cylidrical housing and the other hand around the fan blade's outer round side, the center shaft is stable around the spinning axis.

The fan rotates easily and freely in a circle around the center axis - as a fan should.

HOWEVER, there is a tiny bit of movement or play, maybe 1mm or less, if i gently try to pull the fan shaft out of the motor along the center axis. (As an physical movement anology, imaging pulling off the cap of a Bic ball point plastic pen or magic marker highlighter pen. You pull off the cap along the center axis.)

Might this play cause the occational blood curdling screach? ( For everyone's benefit - my fan motor suddenly stared making a horid noise - like something from a horror movie.)

Pls let me know if possible.

Thanks, Kelly

Kelly,
The axial movement would be a problem if the fan were to contact the housing at the extremes of travel. In the pictures, I was not seeing evidence of that. There is another possibility that the motor rotor could contact the motor housing internally. Try pushing the fan to one extreme and rotating it, then the other way and rotate.
The bearings should not allow much movement as the fan is very close to the housing on both sides of it. Excessive clearance reduces the fan efficiency by allowing air to recirculate instead of being forced out the nozzle to the window.
I did not check the axial free play on my fan when I had it apart specifically but I could disassemble it again and do that.
The axial movement of the fan will be preferentially one direction due to the air pressure it creates acting on the diameter of the closed end of the fan. So it will move toward the open end of the fan. Try that direction and rotate the fan to see if there is any noise.

Bob in Lake Havasu



Edited 1 time(s). Last edit at 03/30/2019 08:04AM by Bob in Everett.

Kelly,
I disassembled my fan housing again to examine the motor. There is a light spring internal to the motor that pushes the shaft toward the fan. The internal thrust bearing keeps the shaft positioned so it would not move axially. There is a small amount of movement of the shaft possible against the spring.
It may be that yours has the thrust bearing excessively worn or the spring is broken.

Bob

Bob in Lake Havasu