I have a 2002 f150 with a 4.6. my heat quit working recently so i replaced the thermostat, blend door actuator and flushed the coolant. All wasgood until i flushed the coolant....shortly after i flushed it it was running good but all of a sudden it was spuddering and running real rough and threw 3 misfiring codes at me..... what did i do please help. i did make a pretty big mess doing the flush.

There are several possible reasons why you may be experiencing cool or no heat in your 2002 Jeep Grand Cherokee Laredo after replacing the thermostat and bleeding the air out of the lines. Some possible causes could include:

1. A malfunctioning blend door or actuator: The blend door controls the mix of hot and cold air that is directed through the heating system. If the blend door or actuator is not functioning properly, it may cause a lack of heat.
2. A clogged heater core: The heater core is responsible for transferring heat from the engine to the cabin of the vehicle. If the heater core is clogged, it may not be able to transfer heat effectively, resulting in cool or no heat.
3. A faulty thermostat: If the thermostat was not properly installed or is not functioning correctly, it may cause the heating system to not work properly.
4. A problem with the water pump: The water pump is responsible for circulating coolant through the engine and heating system. If the water pump is not functioning properly, it may cause a lack of heat.

Thermostat stuck open, low coolant level, stuck blend door or bad blend door actuator, or blogged heater core. Feel both hoses to the heater core. They should both be about the same temp. If one is hot and the other is cold, you have a clogged heater core. If both are hot, then the thermostat is working and you've got a blend air door/actuator problem. Actuator failure is pretty common on these. Remove the actuator and open the door by hand. If you get heat, replace the actuator

Air Temperature Control Blend Door Failure No Heat or no AC (dependes on where door sticks)

In all modern cars there is a tiny DC electric motor driven gear drive that moves a plastic door that blends heated and cooled air from the AC and the heater core, this is called (interestedly enough) the air temperature control blend door actuator. The motor that moves this door fails because the door starts sticking from warping, most common complaint is no heat but it can be no AC as well. To replace these parts (blend door and blend door actuator) you must remove the entire dash from the car. Always have this problem confirmed by a dealer or qualified repair shop as it is a very expensive repair.

Other causes of no heat in the cabin are engine thermostats that are stuck open (engine runs cold) or air bubbles in the cooling system.

The blend actuator door most likely quit working. You will need to replace the unit.

sounds like the air blend door actuator motor is stuck on cold position.

could be coolant temp. sensor

I don't know your vehicle, but does it have a blower door tucked in where the heater core is? If it DOES and that's broken then it could be the whole problem. It would mean it isn't switching from the A/C side of things to the heat side of them. Hope this helps, good luck! Also, just looked up the proper name for what I'm talking about, it's called a "blend door" and I think your car has one. It's what I would check, again, good luck!

Might try checking the temp blend door operation or the temp blend door actuator. If all good there perhaps the control head itself is faulty.

you need to get under the dash board and remove the passenger lower kick panel. ther will be a small motor bolted into the evaporator housing. remove it and manually move the blend door. if the heat gets hot the you need a blend door actuator.