Heater Fan Control Repair FAQ

April 10, 2003

Under constuction

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Courtesy of Peter Florance

I've had my euro e12 since 1984 so I remembered how smooth the heater and AC fan control worked. But after many years of use and hot Virginia summers, the controls started getting sticky and intermittant.

When I replaced the evaporator in the euro I took the time to repair the heater controls. And I was very happy with the results.

Recently I purchased a USA version 528i. The heater fan controls on this car were balky and intermittant; worse than my euro ever was. It really needed help. I got a heater panel from late model 530i and decided to rebuild it so I could just exchange it. It too was sticky and intermittant. For reasons I explain below, I highly recommend rebuilding a spare panel as you don't know what you're going to find in yours.

Removing Panel - I haven't done this yet to document, so you'll have to wait.

Rebuilding Panel - Now that the panel is removed (wasn't that easy?) it should look like the below picture.

Rear of e12 heater control panel (clock removed) with AC themostat and relay
Click on image for larger version

Remove the relay first and then the thermostat. Note the micro switch is rivoted to the clear plastic lens (used for panel lighting) and is not easy to change. Jeff C broke the switch removing the wiring from the donor car, but I can't complain about the price. (-:
But you should be careful pulling on the wiring. I'll be drilling out the rivots and replacing the switch with small screws and nuts.

Once the relay and thermostat are removed you can remove the remaining 3 nut and the contact assembly can be removed. There are spring loaded contacts where each of the AC and heater blower wires attatch. The springs are used to keep the contacts on the assembly tight against the long contacts on the knob. They are now stuck down and don't stay tight against the knob contacts. It will all be a gummy, sticky mess. )-:

Blower switch knob removed
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When it was new the contacts would have flown out (spring loaded) or fallen out, but if you're doing this job, chances are the are all stuck down, held in place by the old sticky grease. If you've had a siezed blower motor, the plastic contact holder could be melted where one or more of the contacts are located. The part number of the contact holder (switch support) is Although the contacts appear different, the book shows 7 contacts all the same My photos clearly show 8, so I'm not sure what the issue is. Push the contacts out, remembering where they go. Collect the contacts and springs and soak in solvent. Replace contacts that are worn flat.

Gummy grease keeping spring-loaded
contacts stuck down on blower switch knob
Click on image for larger version

The knob is removed by pushing it in from the front of the panel. Caution! There is a ball and spring on the side of the knob. Mine was stuck in place by the gummy sticky grease. Save both ball and spring and soak with contacts (above). Note the 2 long curved contacts on the knob are eroded and gummy. They seem to be available (2 required).

Contact strips on blower switch knob
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Clean all plastic part with your favorite safe-for-plastic solvent. I used WD-40 but mineral spirits might work as well. Avoid carb cleaner or other solvents that are not safe for plastic. Clean EVERYTHING.

Contacts, cleaned and lubed; properly spring-loaded
away from knob
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FAQ text and pictures

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