I had the same problem with my cougar.
I flushed the coolant and the heater doesnt blow hot air anymore.
After beating my head for weeks trying to figure this out and asking several different mechanics I found the solution.
On the back of thermostat housing is a hose with a splice in it. You need to remove 1 clamp, pull the hoses apart and open the overflow tank. When you first seperate the hoses you should hear air escaping. Once coolant is flowing from each hose put them back together and your heat problem should be fixed.
Friday, December 7th, 2007 AT 10:50 PM