The heater on my E36 blows cold while idling and hot when engine is running above 1200 RPM(s). There is also no heat blowing through the lower (floor) vents which may or may not be related. Any ideas on a diagnosis will be apprectaited.
Yes do check for leaks in the system and also bleed the system. But it also depends on the year of your vehicle toward the end of the e36 BMW started installing auxiliary water pumps in there vehicles that would help increase coolant flow and idle so as not to drop heater core temperature. I would of course start with the basics like coolant level and bleeding the system. By your floor vents not blowing heat do you mean there is no air flow through the floor vents or just no heat at all? Here is a link from the forums on no heat at idle http://forums.bimmerforums.com/forum/showthread.php?t=683553
Thank you for the diagnosis. I suspected it might be air in the cooling system after hearing a "gurgle" sound a few weeks back. There does not appear to be any air flow (hot or cold) through the floor vents. I will try bleeding the system to see where it takes me..
What year is your E36 and does it have a IHKA or IHKS? The IHKA has fully digital interface and the IHKS uses knobs to adjust temperature and blower speed. If you have IHKA it could be a bad stepper motor that control airflow for the floor vents. If you have IHKS it could be a cable, gears, flaps a lot of things that system is slightly complicated. Let us know how the air bleeding goes.
Problem solved by topping off the coolant beyond the "cold fill level" in the reserve tank and bleeding air from the system. The heat now blows hotter than I can stand it. The floor vents are functioning but just not as strong an air flow as the mid and upper vents. Certainly not worth trying to correct. Thanks for the guidence.
