Heater ECU Problem?
 

I can only get the defrost fan to work when the temperature dial is turned all the way to minimum position. If I set the temperature dial to any other position, the fan will blow full bore for about 3 seconds after the engine has been started and then shuts off. If the temperature switch is turned to minimum, the fan works as it should - 4 speeds on the fan rotary switch and high speed

Any suggestions where to begin would be appreciated
Thanks

Had a similar problem, make sure the fan in the engine compartment is operating. It's directly linked to the heating system operation. Check for blown fuse or bad resistor on the tube from the fan to the heat exchanger. Go over to the Rennlist 964 site lotsa info on heating malfunctions.