Temperature control is by left and right hot engine coolant radiators, after the one AC evaporator, each with its outlet thermometer (that you can see just inside the left and right center grilles). MAX shuts all the flappers except those that blow in your face, sets blower speed to maximum, and thermostat to 60°F. E90 blower troubles. My son's 2009 328 xi started having intermittent problems w heater/ac and heated seat controls. Both would go out and come back, then controls went out for good. Changed fuse, came back for a bit but went dead again. Been to dealer and local mechanic, both sent me home with it working, but went dead again. 193 posts · Joined 2012. #1 · Nov 16, 2013. 2007 x3 3.0 si. Passenger side works fine. The green light on the button doesn't light up and the seat no longer generates heat for the driver side. The fuses diagram found in the vehicle indicate the heat should be 12, 31, 51, 61. The only ones that I find labeled are 51 and 61. 2When the ignition is on, set the heater to the highest temp (84 deg.) and set the fan on low. 3.Hold down the accelerator pedal for 10 seconds then release. This activates the water pump and it will cycle for about 12 minutes to vent all the trapped air into the coolant reservoir (it sounds like a min washing machine). The heater valve should not have any effect on the cooling fan. When the coolant fan is not working properly, it will shut the AC system down to prevent the engine from running hot. If you have INPA or DIS, there is a test to check the operation of the coolant fan. There are 4 stages the fan operates on, depending on the temp. . I'm not sure about your Bimmer, but many diesel (non-commercial) engines bypass coolant past the thermostat to make it to the heater core. If the thermostat isn't flowing once heated up, or not flowing enough, the core will never warm up enough to give off heat. - heater fan speed gets decreased to 75%, 50% or 25%. - seat heating gets reduced or turned off - rear window defogger gets reduced - steering wheel / mirror / washer jet heating gets turned off Or the blower output stage died and that's the one that is draining the battery. _____ A technician will diagnose your BMW 335i heater using the symptoms you report as a starting point. Because your BMW 335i heater is a complex mechanism that uses an electric fan to blow air through a heater core that is heated by the engine coolant, the problem could be electrical, mechanical, coolant-related, or a combination of these systems. As I speed up or slow down the heater fan would slow down and not blow as hard, then all of a sudden start up blowing normally again. This would also happen on some slight bumps in the road also. I also noticed that when I turn the fan setting to the 4th block that is the highest the fan will go. BMW-North. Check out the heater valve (part #64116928495). Feel the hoses going to it. When your car is up to op temp and you have the heater on all hoses connected should be hot. If not it might be jammed closed (common when tap water/mineral build up seizes the plunger.)

bmw e90 heater fan not working