The controls for the heater and A/C do not work all the time

Hi,

Does it only come out from the defroster, or can the blower motor turn on and come from a different area?

I ask because there are two different possibilities. First is the HVAC control module. If this is the issue, I feel it wouldn't be limited to one area, in this case, defrost. If it is limited, then I question the blower motor control module.

The blower motor control module receives a signal from the HVAC module to identify when to turn the fan on and speed. This blower motor module only controls the on/off and the fan speed. So, if it is faulty, it could turn the fan on, but it can't control the air flow direction.
The HVAC module controls everything other.

I attached the wiring schematic, so you have a reference.

Here is what I recommend: This is a newer vehicle. What I suggest is to have the can-bus scanned. CAN stands for controller area network. Basically, all the computers and modules are tied together via a few wires. This type of scan should identify diagnostic trouble codes regardless of the module storing them

Here is a link that shows how it's done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know if that is something you can have done. Also, let me know if you have other questions.

Take care,

Joe

See pics below.

Hi,

If you are unable to control airflow direction either, I have a feeling it is a problem within the HVAC control module. By chance, could you have the can-bus scanned to confirm? It isn't a cheap part and I don't want to be wrong.

Let me know.

Joe

Hi,

Sounds like a plan. Let me know what you find. I'm interested in knowing.

Take care,

Joe