Climate Control Problems

We have a 1991 Lumina Euro (200,000 + miles, 3.1l auto) that has a problem with the climate control.

When the heating/cooling system is off hot air comes from the defrost area. Changing the temp selector from hot to coll has no change. Blows hot when air conditioning is on. The air blows thru the proper vents when the buttons are pushed. Blower works high to low when the systemis turned on.

Gets a little warm (hot) when systme is turned off and driving.

Could this be the control module or deeper in the dash.

Dealer won't give any info, just bring it in and we'll put it on the machine....

Any help is appreciated.

Thanks in advance

Chuck

They have a seperate computer module for the climate control, that why the dealers won't speculate about a cause. When they go bad, all kinds of weird things can happen.

Is this module in the control center or where might it be located?

Can I manually close the blend door without harming the system or should I take a chance and replace the module?

Thanks

Chuck