HVAC wiring harness swap?

My truck is a 2004 and donor was a 2003

So changing only the blower resistor/module may not be enough if the under-dash/I/P harness, HVAC case harness, blower connector wiring, or power feed path does not match the automatic system.

The automatic climate control system may require the complete HVAC harness section, not just the main dash harness and control head.

There is usually a small harness around the HVAC case/blower area that connects:

1. Blower motor
2. Blower control module
3. Mode/temperature actuators
4. Ambient/sunload/interior sensors depending on system
5. HVAC control head circuits

If the truck still has part of the original WT/manual HVAC case harness, the auto control head may not be able to command the blower module correctly. Here is the wiring diagrams so you can see where you are losing power or ground for the blower motor, please start a new question for the radio issue. We only handle one problem per thread, please post your new question here, you must be logged in.

https://www.2carpros.com/questions/new

Here are the HVAC wiring diagrams Check out the images (below). Please let me know what happens.

Alright I’ll give it a shot. Thank you and I will keep you updated.

Thank you!

Update: I went back to the salvage yard and found donor truck. Grabbed the sub-harness for $25 and pulled the rest of the dash out of my ‘04. Pulled old sub out and installed the donor harness in. Plugged the donor climate control module in and hooked the battery back up. Turn the key to on position and air started blowing right away. You just saved a man from burning up in the Houston traffic for the summer. Hats off Stailer, hats off!