Hi all!!
I haven't visited the forum for a while but my feet and nose have gotten colder than I can stand. I have a 2002, 530i with the automatic temperature control and 110,000 miles on it. Lately the heat has become erratic. I msy or may not get heat in the AM. As soon as the temperature gauge gets above the blue region the fan speed increases but the air in the footwell may not be very warm. On other occasions the heat is working fine and after an hour or more of driving it starts blowiong cold air (top and bottom). I can set the driver-side temperature to 90 and get a little warmer air - sometimes hot air but if I set it back to 72 it will be cold. I can advance the stratification control to 3 red dots with little change in top outlet temperature. Frequently, if I stop somewhere for coffee and then get back in the car there is plenty of heat until it decides to turn cold again.

I have replaced the thermostat which was only getting to 80 degree C and now it is stable at 97 degrees. I have replaced the dual hot water heater control valves. I have cleaned the temp sensor in the IHKA control module - it was dust covered.

Any ideas? All I have left is to replace the IHKA control module and I think the dealer has to program it if I replace it ($100?). I have also tried to eliminate any water in the system.

Thanks for your help!!
Bob K.