Hey, I am new to this site because honestly I haven't had a whole lot of trouble out of my Max until now. I have a 97 SE that I can not get any heat out of the vents. The cooling system is full and the climate control along with the vent selector switch both work fine. I can turn the climate control up to 85 deg and still blows a/c. I have heard of a heater core door that is supposed to open and shut when ac/heat are selected getting stuck; could this be my problem and if so how do I access it? I have already dropped my glove box, so if that is my problem where do I go from there? any help would be appreciated.

 

These engines can have pockets of air in the cooling system that will keep the heater from blowing hot air. You need to raise the front of the car maybe a foot and run the engine until the thermostat opens and allows the air to get to the radiator and out.

The heater core door is called the air mix door by nissan. It is operated by a small electric motor located above the ECU. It is hard to see.

from the driver's side footwell:


from the passenger side footwell:


To check and see if the motor is working, get down in the passenger side footwell and remove the plastic panel that covers the end of the ECU so you can see the motor and the connecting arm to the air mix door. Turn the ignition switch to ON (you don't have to start the engine) and change the temperature setting from hot to cold. If the motor is working, you will see the arm for the air mix door move.

 

Ok thanks but I already managed to get the screws out that holds the motor to the housing. If I leave it plugged in and hold the motor in my hand where I can see the accuator should it move? Because it don't. I would reinstall it and do as you said above but as you know those screws are a pain to get to.

 

Even though the motor is not screwed to the housing, the arm on the motor will still move so you should be able to see that. the motor is a self contained unit so being screwed down has nothing to do with the motor working.

 

I'm having the same problem, and the a/c actually stays on, I can here the ac turn on in the engine bay when I turn the heater on. Would this solution work for me too. Or is it an electronical problem that I'll need to track down

 

if you have an air mix door motor problem, it could cause problems with either the heat or the air conditioning.

So get down in the passenger side footwell, turn the ignition key to the ON position and change the temperature from hot to cold while you watch the arm on the motor. It should move.

 

Not sure if you recently replaced your coolant, but mine did that after I replaced the radiator. I burped it by slowly opening the radiator cap while holding a towel over it, and only opening slightly. The heat came back...