Hi, I bought a 04 explorer with a bad thermostat which led to a bad head gasket, fixed that and managed to not have to buy the special tools or time it , but now that its running I don't have any heat. I have complete service records on this vehicle and there was never a complaint of the heater not working. The a/c works and the heat **** will adjust the a/c temp, but no heat. In trouble shooting it I found that I am not getting vacuum to call for the coolant to enter the heater core. When I apply suction to it, it will send the coolant. Even though I wasn't getting the clicking noise, I pulled the blend door actuator and it looks surprisingly good (not looking forward to putting it back in). Anyone have any thoughts on where to look next?

 

you don't have vacuum to open the coolant valve... why pull the blend door ? Check vacuum into the valve and see if the vacuum is gone, or the valve itself is broken.

 

I am sure wishing I hadn't pulled it... I have vacuum on the black line running to the climate controls, but no vacuum on the grey line that goes to coolant valve. The coolant valve works when I manually apply vacuum.

 

Ii don't have a vacuum diagram for that truck. Some trucks have a valve and some don't. The idea is to shut off water flow thru the heater when the heater is not in use. The heater control must turn the vacuum on ... possibly a solenoid ?

You will need to trace back the vacuum and see what turns it on... possibly you don't even need it and can put full vacuum on the valve constantly or remove the valve. I don't think there is any consequence of leaving the valve open.. My F150 has no valve.

 

I found the part that connects the black and grey vacuum line. It is a small black plastic piece on the passengers side and has a round button on it. When the button is depressed the vacuum connects and generates heat. Here is the weird part. When you turn the temperature to cold, it moves the blend door actuator in a way that the little lever thing goes towards the front and towards depressing the button, when you turn it to heat it pulls towards the back and away from the button. But it doesn't generates enough pressure to push the button in. In the other posts I read about the actuator being bad people said that pulling the little lever thing towards the back would cause the heat to work?? In mine it would seem to be reversed?

 

Don't know what state you are in, but I would leave it alone in the summer, and just connect a good vacuum hose in the fall / winter to hold the valve open for 6 months.