I have absolutely no heat in my truck. I've had the thermostat changed so what's the problem?

problems with the heater core , or the water valve , or the temp actuators , just to name a few.
I have absolutely no heat in my truck. I've had the thermostat changed so what's the problem?
Does it still blow just not hot air? If so your heater coil is most likely your problem. Not sure how much that will cost you since that will depend on the vehicle and where you go.

The thermostat has nothing to do with the heater. Thermostats control how hot or cool the engine gets not the heater. It opens and lets water from the radiator flow when the engine gets hot and closes once it reaches it normal operating temp.
I have absolutely no heat in my truck. I've had the thermostat changed so what's the problem?
ryan m has it right on the blend door were the motor sits on it the plastic piece on this trucks crack and the door wont open for air that comes through the heater door 2types of fixes on you have to pull dash out and replace blend door the other if your handy involves removing blend door motor and doing something with it you can find it if you search the internet try searching ford explorer no heat
check to see if the heater core is not leaking. are you losing coolant. the coolant runs thru the heater core and the blower blows the heat into the cab. is the carpet wet on the passenger's side of the cab? if you are not losing any coolant, then your lines (hoses) are plugged or your heater core is plugged. back flushing might help, but it is best just to replace them.
Not enough radiator fluid or a broken radiator fluid pump or the rubber serpentine drive belts needs checking, Look for leaking hoses or for cracks. If you see green or yellow fluid on the ground that's the sure sign of radiator fluid is low or maybe all gone. Open rad cap to see( cold engine only!!!).
You didn't give much info but it sounds like the valve that is suppose to open that allows hot water from the engine to enter the heater core is not working. Or if it is an older truck someone may have bypassed the heater core because it was leaking.
May be a problem with the radiator, the heater core, or a blockage in the water system in the engine
It's probably the temperature blend door on the HVAC unit inside the cab.
have the radiator checked.....solved a problem i had.