Heater Problem

[Hikyuuri]

Hello everyone.

With winder close at hand up north, it is time to fix a heater problem. I first noticed this problem when I was driving at night (40 degrees outside). I turned the heat on, and noticed I was getting no air flow through the vehicle. I set the vent output to the head vents only instead of the feet vents to see if I can feel any air moving, and there was very little. This is with the fan set to full speed, with both recirculation enabled and disabled.

To help locate the problem, I then changed the temp from 90F (max hot) to 60F (max cold) to make the air go through the AC core instead of the heater core. Instantly, I had airflow like I should, with recirculation enabled and disabled out of all vents in the car (head, feet, and defrost).

So, then I set it back to 90F with the fan still manually set to max speed, and the air being directed out of the head vents. Again, the airflow dropped to nothing, and you can hear the fan spin faster as the air is being blocked somewhere.

Since it only does this in heat mode, I believe that the heating core's air fins are clogged somehow (dust, debries, etc). I recently replaced the cabin air filter, so that is not the problem.

Any ideas? I am willing to rip apart the dash to get to the core itself to clean it off, if that is the problem. However, I was hoping someone here may have an easier fix that I did not think of.

Thanks!

[markwb]

It sounds like a door isn't shifting to the correct position.

[DRC]

Bad blend door actuator? Had this same issue on a past vehicle. Look at that option before ripping your dash apart.

[imidazol97]

I set the vent output to the head vents only instead of the feet vents to see if I can feel any air moving, and there was very little. This is with the fan set to full speed, with both recirculation enabled and disabled.

To help locate the problem, I then changed the temp from 90F (max hot) to 60F (max cold) to make the air go through the AC core instead of the heater core. Instantly, I had airflow like I should, with recirculation enabled and disabled out of all vents in the car (head, feet, and defrost).Thanks!

The good news is that by taking off the plastic sound covers under the dash you can easily see the actuators on both sides of the center stack HVAC box. They have a white plastic part and you can see it turn easily IF the thing is moving when you change the buttons on the dash while your head is on the floor!

I am not clear of what is not happening, but it sounds like you cannot change the direction of air flow. That is done by 1 actuator.

Also there is an actuator to change the blend door (2 on the dual control model which I presume SSei is.

Does your temperature change of the air when you change from 60 to 90, wherever it's coming out?

It may help if I explain that all the air goes through the AC condenser all the time. The blend door lets air bypass the heater core and changes the amount of bypass, so that it blends hot air with the air that came through the AC condenser that didn't get heated to give you the chosen temperature.

I'll look for diagrams of the location of the actuators...
These _may_ be visible without removing the underdash hush panel


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