Hi all-
I have a 1992 745T. The blower on the heater/ac has quit on me. I figured it was just a simple blower replacement. Not. After I removed the blower, it did not look that bad. I hot wired it directly to a 12 volt power and it works fine. So I did some more poking around. I checked all the fuses and they all are intact. I checked the resistor pack and It does not look dammaged. No blown diodes, or burned looking resistors. I then looked at the HVAC controll unit. Here is what I found: The blower fan will not work in any speed setting. When I move the heat controll knob, the servo that moves the air door does not work. The switch that controlls the outside/recirculating air does seem to work. The knob that controlls the air vent outlet settings apears to work as I can hear hissing and doors moving inside the air plenums when the knob is turned to different positions. The AC on/off switch apears to work, but the AC compressor and freon charge has not worked in several years but I am not concerned about that since I live inMaine and have little use for AC. I suspect that something in the controll unit with the 3 knobs and 2 push button switches is not working (probably the blower knob or the power source to that congtroll).

So here is the question: How do I test this unit? I have removed it from the car (looks a little like a grenade went off in the dash board). Is there a way to test the individual controlls? How is this done? I am not interested in repairing the AC, but I do need the blower and heat to be working. for the winter. Please help. Thanks.

1992 745T, 294,845 miles and still going strong.