Getting right down to it...my heat and AC just stopped working. The digital read-out switches from auto to econ without a problem. The temperature read-out works just fine as well. The problem is that the heater and AC doesn't respond when I want to heat or cool the cabin. The defrost will blow, but it doesn't actually defrost; it just blows cool air. Only knowing the basics, I am guessing that it is my thermostat. Before I go out and pick up a new thermostat and replace it, is it probable that this is the cause? Is there something I can do to pin-point the problem? Any input will help...

 

has the car had any cooling system problems, such as a bad radiator or bad water pump recently?

 

Nope. I've had no problems since I have purchased the vehicle 2 years ago.

 

Are there two thermostats in my 93 Deville? I took the thermostat (the one in conjunction with the radiator) out and tested it in a bucket of warm and cold water. It operates just fine. The reason I'm asking if there are two thermostats is, how does the climate control measure the temperature inside the cabin? How does the climate control prompt the blower motor to turn on and off according to the in-dash climate control temperature setting?