2002 grand am no heat

[lisarose]

My 2002 grand am does not have any heat. It is not overheating and the blower works fine but it only blows cold air. When I noticed that the heat wasn't working I also noticed that the rear defrost light and a/c light on the butons wasn't working either. They had been working previously. Could it be a fuse of some sort or something else?

[gmtech1]

Do the rest of the controls work? Just no heat?

[lisarose]

it will change from defrost to floor or vent. I don't know if the a/c works because it's about 35 degrees in northern Indiana and it just blows cold air. The knob that changes from hot to cold is fine. We took the knob off and it moves fine it doesn't spin.

[gmtech1]

Check the coolant level in the radiator, if its ok check and make sure the both hoses at the heater core are hot after the car warms up. If one is hot and one stays much cooler, your heater core is plugged. If both are hot and still no heat, there is a problem with the temp door circut.

[lisarose]

Both of the hoses are the same temp. Where is the temp door circuit and how can you check that?

[gmtech1]

The "circut" is everything that controls the temp door, from the switch to the door itself. The temp door actuator can be accessed by removing the glove box. It's mounted to the left of the glove box on the HVAC case, it'll have a electrical plug going to it. You should be able to remove the actuator and adjust the temp and see if the actuator moves, if not, it probably needs replaced. If it does move, try and manually move the door, it may be broken.

[gmtech1]

If the actuator drive is visible from the back of the actuator, you wont need to remove it to see if it's working.

[lisarose]

we see the black box that must be the actuator. We do see the doors moving but could it still be the acuator? Does that also control the heat coming from the heater core? The doors move and change the heat from defrost to floor and vent. But the temp stays cold.

[gmtech1]

Ok, the coolant level is good, you are sure the heater core is not plugged(both hoses are hot), you can see the temp door actuator moving. The door has to be broken. Remove the actuator and attempt to move the door by hand. If the end of the door can be pushed into the case, the door is broken. If you can moved the door to full cold and full hot and still the temp won't change, there is another problem. I'll bet the door is broken.

[Tech II]

The doors move and change the heat from defrost to floor and vent. But the temp stays cold.

The actuator that changes air flow is the mode door, not the temp door....

You want to look at the actuator for the temp door.....should be a silver circle visible on the black box.....when you move the temp lever from cold to hot, that circle should rotate......Like GMtech1 said, if it moves, then remove it and grab the linkage to the temp door and move it manually....if it doesn't move, it's broken....

If the circle doesn't move when the temp is changed, but if you remove the actuator and then manually move the door linkage and get heat, it's the actuator that's the problem...

[lisarose]

If it's the temp door how do you fix that

[Tech II]

You really don't want to know......If that temp door is broken, the whole HVAC module has to come out....that means removing the dash.....

Luckily, I have never seen that happen.....it's usually the actuator, or the actuator is not getting a signal from the control head....

[lisarose]

Thanks everybody!!!! It was the blend door acuator. We replaced it and now we don't have to bundle up to go anywhere!