Replacing Heater Blower Motor
on a 1981 BMW 320i
(North American model)
There seems to be a number of posts (on www.BMW320i.com ) referring to the heater blower motors. I replaced mine in November of 2002, and in so doing learned a few things that I can pass along.
My blower motor is a SOFICA manufactured model. If yours is a Behr or Bosch, the process will be similar, but the motors are generally NOT interchangeable.
I use the Haynes repair manual, which does not give very accurate information on this particular model of blower motor. What tools are needed? Here are the main tools you'll need:
§ A common screwdriver and a Phillips screwdriver § A 5/16 inch (preferably socket) wrench § A 10 mm socket wrench with about a 10 inch extension bar § Good lighting § Good humour!
What is the removal procedure? 1. First disconnect your negative terminal of the battery. (You will thus avoid short-circuiting the motor leads onto the firewall when you disconnect
them.) 2. Remove the five bolts holding the weather cover onto the top front of the firewall. You can find them!
5. Remove the distributor cap, or at least the one wire on the top of it closest to the firewall - that one will get in the way when you try to
remove the weather cover. 6. Raise the ends of the weatherstripping at the top outer edges of the firewall, as they tend to hold the weather cover in place; AND unhook the
cables from their supports along the front of the weather cover. 7. Wiggle off the weather cover. It should come out at the bottom with a bit of resistance (old sticky-both-sides weather stripping hidden
underneath), and then rotate up and outward towards the front of the car. 8. Remove both metal weather shields outboard of the motor/turbine assembly using the 10 mm socket with extension handle (see photo C).
Otherwise, you cannot move the casing covers outward and remove them from your work area.
3. Remove the four
Phillips screws holding the top edge of the weather cover (see photo A). 
4. Remove the two Phillips screws holding the module on the cover/firewall and
the screw holding the cable support to the side of it (see photo B).
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Now you're able to see the motor/turbine assembly. Unplug the bayonet type wiring from the motor.
11. Unlatch the motor securing strap, and with some hand pressure pulling outward on the lip of the firewall, lift the motor/turbine assembly forward and out of the work space.
9. On each turbine side, release the top casing lock mechanism (see photo D). This is quite different from the Haynes manual - my top casings do not have securing straps, but instead have VERY hard to get at
tabs: one at the top, and one at the bottom, which need to be disengaged by a common screwdriver before they will let go! (The bottom casings stay on the car.)
10. Even after the tabs on the upper casings are unlocked, it's not easy
getting the rings off both sides of the turbines. Gently pry/wiggle off the outer rings and the inner rings (see photo E), and remove the top half of the casing by
sliding it outward in the trough/work area created by removing the metal weather shields.
What is the replacement procedure?
You guessed it, it's the reverse of the foregoing! The hardest part is getting the upper casing rings in place - note that the flat edge of the outer ring goes downward; and then locking the casing securing tabs
(upper first, then lower). Here is a photo of the passenger side: upper casing, outer ring and partial inner ring. The rings are groved to fit the casings, and are a tight fit.
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Notes: My local BMW dealer custom ordered a replacement motor for me - I specified a SOFICA type motor; but when it arrived, it was a Bosch type, and it would not have fit at all! I searched the Edmonton area for options, and struck out.
While my original cages were held on by Allen screws (and could
therefore be cleaned up and reused if necessary), the new cages were a press fit held in place by special toothed lock washers. However, I was able to "drift" the cages into their proper positions by
securing a large, depressed-head bolt vertically in my vise and, while holding the bottom shaft on top of the depressed head, hitting the top end of a metal bar while the bottom end was down in the cage on
the backside of the nylon axle. Turning the cage after a couple of hits in order to distribute the force around the nylon seemed to keep the axle from being damaged. One last tip:
while doing the "drifting" of the cages on the shafts, apparently a resistor-type of metal bar bent over enough to just touch the
motor windings. If I hadn't spun the cages by hand after doing the drifting, I wouldn't have heard the clicking caused by that contact - and I
would have been quite angry at myself if I had put it all back together on the car and turned it on in that condition!
As a minimum, I suggest you put the new assembly on the car and turn it on BEFORE finishing up the installation of all the rest of the parts. Good Driving!
I finally found one online at thepartsbin.com; but when it arrived, I found the squirrel cages were not spaced properly on the motor shafts!
There is only about one centimeter (1/3 inch) of room on the left and right of the squirrel cages in their casings.