Front AC blows warm, but the rear works

Hi,

It could as simple as the blend door or air mix control motor is stuck or the gears are stripped. What happens is, when you change the temp this door moves and directs the air over the evaporator which cools the air. When this breaks/fails, the air is not directed over the evaporator so it is only passing over the heater core which heats the air and then it comes into the cabin. This is why when you used to raise the temp or lower it, the actuator would grab the gear again or unstuck itself and it would start working. Now that it does not work, most likely the gears are stripped and it can no longer move the door.

The rear works because it appears your vehicle has a rear system that is completely separate.

There is a chance that a temp sensor is reading improperly but based on what you described, the actuator makes more sense. We would need to hook a scan tool to the computer and see what the temp sensors are reading to rule this out. Again, it is unlikely because it appears this stays blowing hot even when you are not using the Auto setting. Normally we only use the temperature sensors to control heat/cool in the auto setting.

https://www.2carpros.com/articles/replace-blend-door-motor

They are the same component. The blend door and air mix are the same thing just different names. The link I sent was just a generic guide to help explain this function.

Sorry for the confusion.

I just did a search for the MDX air mix door and found the same pricing spread. Basically the price difference is just the quality of the product. You can't really go wrong with this because they are just plastic gears so I would not be scared of the cheaper items. Just make sure they say they fit your year and model vehicle. Then they are for the air mix door or the blend door.

I could not find any more detail about your specific vehicle but here is a video from an Acura TL. It is a little different but these components are in about the same location but the operation is the same. I would verify the part number that is in the video to make sure it fits your vehicle but it is another option if it does. Clearly he made this video because he didn't want to pay the price. I am not sure you would be able to fix yours like he does but it may be worth while to take it apart and see. Worst case, you have to replace it.

Hopefully this helps. Please tell me what else you need and I will try to assist more. Thanks

https://youtu.be/Hyu0TKtbuAM