Just started having a problem with the heater on my 2005 Tundra. When I'm idling/not moving the air temp drops to outside air temp. When moving I get plenty of warm/hot air flow. The temp knob seems to be controlling the temp ok (again, when I'm moving) and no effect when I'm idling. Same situation with the defrost.

 

Don't need two threads on the same topic...

 

Thermostate is stuck open replace it

 

Well, us 86-95 peeps may not be able to help you much, you might want to post over in the Tundra section.