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Thread: Z3 Roadster (E36/7) Heater Control Issues
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Old 12-08-2012, 07:29 AM
marty505 marty505 is offline
Officially Welcomed to the 'Fest
Location: New Mexico
Join Date: Nov 2012
Posts: 166
Mein Auto: 99 Z3 M Coupe/99 540i
Heater Control Valve

Sounds like your heater control valve is sticking open. This valve has a solenoid that opens when +12V is applied and closes when voltage is removed, this is how the car regulates the heater output. Sounds like yours opens just fine but then hangs up and doesn't close. Usually they don't stick wide open, typically they partially close and "leak" hot coolant through the heater core and are a common culprit for poor AC performance. Here's a link to the RealOEM page showing the typical Z3 control valve (item 4 in the diagram) You should double check the valve P/N since I didn't know what engine you have. The valve is located on the engine firewall and is simple to replace. It can be bought from any number of aftermarket BMW parts suppliers for a bit less than the price shown on RealOEM.
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