91 Buick Lesabre -defrost/heater not working properly!!

probably a vacuum leak. Check to see if the hose connecting to the vacuum tank on the firewall came off. On my car the vac tank is to the left of the washer pump. The hose connects on the bottom . There may even be a plastic valve connected to the hose like on mine.

You might also have a bad vacuum diaphram or loose hose under the dashboard. That would require removing the lower black dash trim panels and listening for a loud SSSSSSssss noise.

Good Luck

========= Harryface =========

~_~_~_~_U.S.A._~_~_~_~_~_

~~~The Former Fleet ~~~

I was thinking the coolant might be low and the lines are getting air locked. Does it only go cold when you are at idle, and at highway speeds it's fine?

Steve

Sounds like your engine is out of coolant. Better check it before it blows up.

As far as checking the vacuum tank and hose, I might suggest you take the tank off and reseal it with some silicone sealer, My same car although it had heat would not blow air from the correct vents. It seems the tank was leaking from the seams. Took me forever to find that one. Good Luck JRE