Heater blowing cold air

[cduggan67]

Hello:
I have a 2001 Ford Explorer 4.0 and one minute the heat was blasting the next thing it was blowing cold air. I've changed the thermostat, water pump, flushed the entire cooling system and it's still blowing cold.
Any advice on what I can try next or what you think the problem is?
It's -4 degrees here....any help would be appreciated.
Thanks.

 

[Bobmbx]

Hello:
I have a 2001 Ford Explorer 4.0 and one minute the heat was blasting the next thing it was blowing cold air. I've changed the thermostat, water pump, flushed the entire cooling system and it's still blowing cold.
Any advice on what I can try next or what you think the problem is?
It's -4 degrees here....any help would be appreciated.
Thanks.

Check your heater control valve for proper operation. It is normally located on the heater core supply hose. It is vacuum driven and shuts off the flow of hot water when the AC system is calling for cold air.

It will look something like this. Your exact location and design may vary. But it will be on the heater supply hose.

 

[cduggan67]

Thank you!!

That was the problem! Thank you so much for your help!