This 1997 GMC C1500 came in for some other a/c service and I asked the customer about the blower working. He said it worked fine and asked why I wanted to know. I told him of the endless requests that I get for information on the blower systems on these trucks and how I wanted to meet my readers needs. He told me to take it apart and take as many pictures as I wanted to.
This information applies to 1995, 1996, 1997, 1998, 1999 old body style C1500 & K1500 Chevrolet and GMC pickup trucks and SUV’s, 1995-2000 C2500 and K2500 trucks and SUV’s, 1995-2002 C3500 trucks, and 1995-2001 K3500 trucks. SUV’s include Escalade, Suburban, Tahoe and Yukon. I will have to break this information into several posts, so please be patient. This part will deal with the blower switch and its signals. To gain access to the blower switch the dash face has to be removed.
Grasp the edge of the dash face panel and pull towards the steering wheel.
When the panel is pulled out far enough, depress the locking tab on the headlight switch wiring and unplug the harness.
As the face panel is worked loose, the switches to the left of the radio and a/c controls will need to be disconnected. Most of the time if the small panel will pull loose from the main panel it will be easier to work with.
It is easier to do all of this with the shifter handle pulled all of the way down to the D1 position.
As the trim panel is rolled away from the dash, the plastic will need to be flexed slightly in order to remove the face panel.
Now that the trim panel is out of the way, the a/c control head can be removed. There are two plastic clips that need to be released. One on each side.
Then the a/c control head assembly can be pulled from the dash.
The latch that holds the harness to the blower switch is on the underside of the assembly. Depress the latch and unplug the harness.
This harness connector is okay of course, but many times the brown and orange wires will be burnt. If there is any heat discoloration, the switch and the harness connector must be replaced at the same time or the condition will return very quickly.
The entire control panel does not have to be replaced if only the blower switch is damaged. There is one screw that holds the retaining plate in place. Remove the screw and retaining plate. There will be two smaller plastic clips that hold the switch to the main housing. Most of the time they will break due to age. That is okay as long as the main retaining plate and screw are installed after the switch replacement. If you need to order this switch please click here.
- Terminal “A” = Light Blue wire, Speed M2, switched power to blower resistor
- Terminal “B” = Tan wire, Speed M1, switched power to blower resistor
- Terminal “C” = Yellow wire, Speed Low switched to blower resistor
- Terminal “D” = Dark Green wire, A/C disable signal, switched power to connector C3, terminal “4”
- Terminal “E” = Empty
- Terminal “F” = Empty
- Terminal “G” = Brown wire, 12 volt ignition supply from fuse #12 (25 amp)
- Terminal “H” = Orange wire, Speed High, switched power to terminal “C2” of blower relay
Using heavier wires and terminal will cause no problems except for possibly finding the right splicing terminal to connect the wires. I will normally use the correct terminal for the larger wire and then strip back more of the smaller wire. Then I will fold the smaller wire back on itself several times until it fits snugly in the splicing terminal. Also the 4172 kit from The Electric Connection come with various sizes of wires.
I have a kit that is the ac delco. The wires in it are 10-12 gauge and truck wires are a smaller gauge is this all right? 1998 k2500
If the heat is only present at the brown wire near the blower switch and nowhere else in the system, I would recommend replacing the harness connector. You will likely have a loose terminal that is generating the heat. The part number is 4172 and can be found at
http://www.the-electric-connection.com
I followed your posted instruction regarding the electrical issue on my 1998 chevy truck. I replaced the blower control head with new unit/replaced the Heater blower resistor/replaced the resistor wire connection/installed a new blower motor. However the brown wire thats attached to the blower motor speed switch gets extreamly hot. You indicate that wire is #12 fuse/ignition. What do I need to chase to eliminate this hot issue?
I’n glad I did not put the control head back in the dash location. I would have not known the issue existed. This issue has been around since I purchased this truck new.
Hi Eddie,
Somehow your comment got sent to a spam folder. I know this is probably too late for you but the ground terminates at the rear of the passenger side cylinder head. On some year models there is a three wire in-line connector at the right side of the glove box that will burn out.