Here’s how a dual zone automatic climate control system works in your car:


I took apart the HVAC mixer from underneath the dashboard of an Infiniti G35 to see what’s inside and how it works.
Here’s the dash removed:



Here’s the entire HVAC system removed from the interior of the vehicle:

The actuators that control the flaps for the recirculate, temperature mix, and modes all have a small motor and potentiometer inside and are controlled with 3 wires on the CAN Bus.


The blower motor is PWM controlled so there’s no need for a blower motor resistor:

Here’s a look at the mixer box assembly with two actuators in black boxes on the side:

Here is the temperature mixer flap. Since this is a dual zone climate control system, the entire box is split into two after the evaporator and this flap controls the heater core by pass for each side individually:


Here’s what the inside of the evaporator core looks like. Refridgerant flows through and absorbs heat from the air cooling it and removing moisture:


The thermostatic expansion valve is the brain of the A/C system. It controls the flow of refrigerant based on the differences in the inlet and outlet temperature of the refrigerant to make sure it doesn’t freeze up or run too lean.

And that’s pretty much what’s inside the HVAC system under your car’s dashboard!

 

Dude dude dude! That video made me smile. Not sure though that the pointer would help brighten my smile though.

Props to you. Awesome stuff. Thanks for your efforts in sharing it with the community.

 

I second the compliment above, your knowledge and desire to share it is amazing. Thanks!!

 

Nice work man! Keep up the awesome stuff!

 

Damn, that looked like a huge project

 

Another awesome video, your driveway is starting to look like an ecological disaster

 

Thanks very much everyone!
It sure was a lot of work to get the dash out and the box apart, but it goes to show if something needed to be serviced (such as replacing the expansion valve, heater core or an actuator) what work would be involved.
My driveway sure was a disaster when I was taking this car apart! More or less the big pieces are gone and now I just have sub components left to detail.

 

Wow I've always wanted to see it apart. Can't imagine the work it took to take apart. Many thanks.