When cars were first created, the only kind of climate control available was cranking open a window to let in fresh air. The invention of air conditioning and heating changed the way that people drive because now they could drive in hotter or colder conditions than normal, and still be comfortable. The A/C controls on a GMC are all electric nowadays, with no mechanical connections at all, and are fairly easy to remove and reinstall. In this case, the project vehicle is a 2004 GMC Sierra, but the process is similar for other vehicles as well.
Use your left foot to push down the emergency brake and lock it in place. Place your right foot on the brake pedal and put the key in the ignition. Turn the key to the "On" position, without engaging the ignition completely, and shift the automatic gear shifter into the lowest position then tilt the steering column to its lowest position.
Pull off the bezel that goes around the dashboard manually to release the clips. Place the dash panel to the side out of the way. At this point, you can shift the truck back in gear, turn the key off and take your foot off the brake.
Unbolt the A/C control panel using the 1/4-inch ratchet and socket then slide the panel out of the dashboard. Unplug the wiring harness from the back of the control panel and set the old panel to the side.
Plug the wiring harness into the replacement A/C control unit and bolt it into the dashboard using the 1/4-inch ratchet and socket. Place your right foot on the brake pedal and put the key in the ignition. Turn the key to the "On" position, without engaging the ignition completely, and shift the automatic gear shifter into the lowest position, then tilt the steering column to its lowest position. Reinstall the dash bezel, then shift the truck back in gear, turn the key off and take your foot off the brake.
