I have an '88 with climate control. The Heater / AC Blower motor will only run on high speed - and continues to run on high speed even when car is turned off, and the key is removed from ignition. I have to unplug at the fan motor, or the blower motor will continue running on high speed, and drain battery. I was thinking the relay? Any suggestions?

 

You have a bad blower control module. Unplug the connector to the module and the blower will stop. The module is solid state with a transistor that is controlled by your a/c control head. Seen it and replaced lots of GM blower control modules on climate control units. [8D]

 

Thanks for the information- Does $525.00 sound right for the blower control module "Kit" as quoted by Chevrolet Dealer?

 

Check with a local parts store that carries A/C Delco parts. The Delco will be cheaper than the dealer and yes, it is expensive. []