Just put a new thermostat in and it still don't work. Also had the radiator replaced before I noticed the heater not working. What could be the problem?

 

What is the concern? Blows cold, blows warm, or not at all?

 

it doesn't get warm. seems to be consistent with the temp inside the vehicle. fan works fine.

 

Is the water temp normal? Possible a heater core problem, possibly clogged. Maybe next time you drive feel the two lines going into the cab of the vehicle. They are usually on the passenger side behind the motor. Becareful, they might be pretty hot. They should be close to the same temp.

 

Yeah, I'm also leaning towards the heater core being restricted, if indeed the coolant level is full. Recheck the coolant level in the radiator and add if need be. If it's full, more than likely the heater core is restricted.

 

Thanks for the info. Thats what I was thinking also, but how do you flush it.

 

You need to follow the heater core hoses to the water pump and intake manifold, and then disconnect them from there. Take the garden hose and hook it to one of the hoses. Let the water flow while looking at the water coming out the other hose. When it starts to clear up a little, stick the garden hose to the other heater core hose. Repeat this as many times as needed until the water coming out is clear. Once the water is clear coming out of both heater core hoses, reconnect them to the water pump and intake manifold. Then top off the radiator and over flow reservoir with coolant. Let the truck reach operating temperature and see what kind of heat output you have from the heater core. Also, check and make sure there are no leaks from the hoses that were taken off. I believe Prestone has an additive or antifreeze with an additive to aid in keeping the cooling system from restricting the heater core and rest of the cooling system.

 

try cleaning the sensor above the drivers door it looks like a speaker grill pull it off and use a q tip and wipe it off this fixed mine boy what a difference.
JIM