Heater blows cold air on 1999 Ford Explorer

Heater blows cold air and after 20 miles or so it will start getting warm. It then starts blowing cold again. It goes back and forth like this while running.

by in Pelham, GA on March 17, 2011
1 answer
ANSWER by on March 18, 2011
Sounds like a classic thermostat issue. However, if the engine is hot enough, it could be a temperature blend issue inside the dash.
Related Items:
Heater core is fine, it blows cold air, the air conditioner works fine. not sure what the probl...
driving at 55 mph in 7 degree F. temperature my heater only blows cold air
when i turn heat on no heat just cold air