craneman61!

I have a 96 coupe with auto air. I have read everything I can find but can't find this exact problem. When I crank the engine my HVAC comes on auto. I can turn it off. When I turn it on auto the compressor comes on but the fan does not blow. I can run the fan up and it will blow. The fan does not blow unless you run it up manually on any setting. I ran the diagnostic and these are the readings: Parameter 1=73, 2=122,3=83,4=198,9=00,24=128 and 34=-153. I did have a blend door problem but I have fixed that. I have taken the control head out and cleaned it but no change. I used to have the blinking light but since I fixed blend door that is gone. Could this be the control head itself? Why would it come on auto when you crank engine? Why will fan run on manual but not auto? Help please! I have been working on this off and on for a month. This is driving me nuttier than I already am.

Cliff Harris

There's not much in the HVAC control head. Just the buttons and the electronics to drive the displays and communicate with the HVAC programmer. Everything else is done in the HVAC programmer.

pcolt94

I would first look at the blower module connector for any burnt connections. Look at it carefully for corrosion or any burnt or loose wires in the connector. Of course the module itself could be acting up as well.

When the main car battery is connected, the control head comes on in auto with the fan running. The symptom reminds me of this. Power (12 volts) should always be on to the programmer thru fuse 43. Fuse 10 is "hot in run" and feeds control head and programmer. Make sure the fuses are good.

The programmer can make the control head do funny things. I have repaired several for bad filter capacitors (4) and have a link with info for it. If you have checked everything else and come to a dead end, then I would suggest to do the programmer repair. It's a bear getting it in and out however the actual circuit repair is the easiest part.

craneman61!

Thanks guys I'ii give these ideas a try later this week.