No heat

I know its summer time but the other morning I was driving and my windshield fogged up. I set the defrost but the air coming out was so cold it made it worse. I turned the heat up on the controls but it never did warm up. I switched to floor, vent, etc. and all blew out cold air with the heat turned all the way up. I checked the coolant level and it is fine. Any suggestions?

Where did you check the coolant level? In the plastic reservoir or in the radiator? Is the engine reaching normal temperature? Does it take a long time to get there?

I checked the coolant in the plastic reservoir, though the engine was not hot it had already cooled down some. The engine is reaching normal temperature according to the gauge and it appears to take the normal time to reach temperature.

How about make model and year and does it have one of those fancy computer controlled systems?

It is a 2002 GMC Safari van. I don’t believe the heating system is computer controlled. Could it be the cold/heat control switch is bad in the dash?