My 88 735i has a heater problem: All the knobs are on the cooling mode, but heat is coming out of the vents regardless. I took the sword out where I have noticed that a MOSFET is charred, hence only the low and high speed for the blower ( I think this is the reason), but I suspect a heater valve being defective. Is there a procedure to test the heater valve?
Thank you,
http://www.bimmerboard.com/forums/posts/841827/
how to disassemble the heater valves is shown on my website below, maybe they are dirty and stuck.
Shogun tricks and tips for the E32 series are HERE!
Could also be bad IHKA module. Replacing the heater valves with a new bosch unit did not fix my situation. Reflowing the solder joints on the IHKA unit helped fix the constant heat problem. Probably the better route is to get a rebuilt unit from ProGrama eventually....for every electronic bit on this car.
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