My 2009 Ford Explorer Eddie Bauer has a strange heater issue. It is not an issue with the door. With the engine off but key turned on I can switch the temperature control from cold to hot and hear the door switch positions. Once the engine warms up if the fan speed is on the lowest setting I can feel warm air coming out of the defrost. If I increase the air speed the first burst of air is warm but it quickly turns cold. I seems as if there is a low flow of coolant circulating through the heater core. The air flow quickly dissipates the heat from the heater core quicker than the coolant flow can reheat it. I don't know if I have a vapor lock or what. that is the only thing I can think. of. Does anyone have any ideas? If it is a vapor lock, how do I clear it to get the coolant flowing again?

 

Hi Dave,
You could be right regarding some trapped air in the heater core. The question is how did it get there?
If work was done on the cooling system or the coolant level went down for some reason , air can get in there that way. If none of those apply, then this is what I would look at.
When the engine reaches operating temp, both heater hoses should be about the same temp. Are they?
If your vehicle has a temp gauge, does it go up to almost half way? If not, the engine thermostat could be stuck open and would require replacement.

Suppose we wait until you either check those 2 items or have some one else do that ? Let us know what you found and we can go from there.

 

Thanks for the feedback. The temperature gauge shows normal operating temperature. I have also seen this when coolant is very low but that is usually accompanied by the temperature gauge showing cold. I will confirm coolant level then warm up the engine and check the hoses.