1999 Mercury Mountaineer

Heater problem
1999 Mercury Mountaineer V8 Automatic

We have replaced the coolant and the thermostat but still have no heat in this vehicle. It blows cold air only. Can you suggest what else we should look at?
November 4, 2010.

With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If they are.

The temperature is controlled by the use of an air mix door that is operated by an electric motor/actuator. This door can be jammed or the actuator can be inoperative or have stripped plastic gears internally.

Nov 4, 2010.