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Addendum to heater box refurbi. article - IMPORTANT UPDATE

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I'm adding some notes to Chris Blumenthal's excellent FAQ article http://www.bmw2002faq.com/content/view/73/32/

1) I have confirmed that the new replacement Behr heater fan with Bosch motor (made in Spain) has reverse polarity as compared to the original Bosch German motors. Looking at the motor with the (2) terminals facing you, the left-hand (Male spade) is negative (-) and the right-hand (Female) is positive (+). While "bench testing", I connected my new fan up to the original wires (red + from left-side of the resistor board and brown - from the right-side of the resistor board) and it turned backwards, blowing air out of the box.

2) The fan blades may be slightly different on the new assembly, which may interfere with both the plastic cage and fresh air flap (when fully opened). I'm having trouble getting clearance after multiple "adjustments" to the blades.

3) The red plastic bushings that secure the fan to the motor shaft may push apart from each other, causing the fan to become wobbly (See note 2). Make sure they are pushed up tight against the fan.

4) When re-installing the top cover (with fan) to the main housing, leave the (2) large heater core tube grommits off until you have positioned the top onto the box. I found this method is much easier. To fit the large grommits, start by fitting them at a sharp angle to the cover, then use a small flat-blade screwdriver to carefully work them into place. New seals are definitely needed when you are re-doing your heater.

4a) Pre-fit the small grommit for the heater valve in the cover, then fish the cable thru the grommit while tilting the cover down into place.

5) Instead of using rivets to hold the top cover to the box, I purchased some brass hardware from Lowes'. I got this idea from Keith Kreeger's website.

Here is what I used:

(6) 10-24 x 1/2" long round slotted machine bolts

(12) #14S flat washers (above and below the box)

(6) 10-24 nuts

6) Instead of using foam weatherstripping on the cover to body, I'm going to use EDPM Rubber weatherseal ($ 6.28 from Lowes'). MD # 63669 5/16" x 19/32" x 10'

See my pictures - hope this is helpful to someone.






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More pictures added showing the fan clip details. I've never seen this clearly before. You must make sure the bottom of the clip engages in the plastic motor housing correctly. The clip may need bending so it snaps into place on the top.



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Two more pictures added showing the plastic snap-on cap to protect the motor bearing. I transferred the one from my old German motor onto the top of the new Spanish motor.



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THANKS very much for taking the time to contribute! I have updated the article with your text, and am trying to remember how to upload images (its been a while! :D), so the new pics should be up soon also. ;)


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Just when you think it's safe to re-install everything and "button it up"...

I put the refurbed box back in today and hooked up the battery. The fan spun backwards, sucking up thru the vents and out the cowl!!!

Since I wasn't about to pull the box back out (I had one hellova time getting it back in), I made some wire terminal jumpers to switch the leads at the motor.

I must have done something wrong because I tested the motor multiple times connecting the battery to the + and - terminals outside of the resistor box.

I apologize if anyone followed my advice and then had problems.




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