Replacing AC/Heater Fan Switch

[LCato]

I recently purchased a 1970 C10 with Air Conditioning and now I’m beginning to address a few minor issues. The current AC/Heater Fan switch had a little “melt down” prior to my ownership and isn’t working, so I’ve picked up a replacement switch I need to install. I’m not sure if I need to remove the entire Temp Control Assembly and/or other under-the-dash "stuff" to swap out the switch... or if there is a better way? Any guidance on the best way and recommended steps to accomplish this task would be greatly appreciated! I’m a newbie at this so don’t hold back on the details!

[BrentBTK]

This isn't helpful, but I'm curious also. I just picked up a '71 with AC and the controls are all shot. BTW, new user from the ATL area as well

[LCato]

Thanks for the post BrentBTK – my exhaustive search turned up nothing around this topic so perhaps its really simple and I’m just overthinking it!

I see I can remove the two large screws that attaches the Temp Control Assembly to the Dash which allows it to move some, but the Hoses and Duct work immediately behind that Assembly are packed in tightly which prevents me from lowering the Assembly below the Dash so I can replace the Switch. Before I dive into this too aggressively and disassemble too much, I’m hoping someone will chime in on what’s truly needed.

[BrentBTK]

Yeah, I just started looking at mine yesterday and became pretty quickly overwhelmed. I'd like to just wire a temp on/off switch for the fan to have some heat in the cab for now. All the ducts are shot and everything seems impossible to get to, lol.

[Rich72C10]

I went through this during the summer.

There are two screws that hold the switch on the the controller, which are blocked by the ignition. So I removed the two screws holding the controller to the dash and pulled it out a bit. There should be enough slack to carefully pull it out to get to the two screws for the switch.

The vacuum hoses will surely pull off, so check their positions first to get them back on after you reinstall the controller.

When I ordered my switch, I also got a new connector and other bits and bobs for to insure everything was okay in the path of the switch. I was pleasantly surprised that as bad as it looked (melted connector) the wiring was fine once I put them into the new connector.

Manes Truck Parts

1. A/C Compressor Switch - 1967-72 Chevy/GMC Truck
2. A/C Switch Plug - 1967-72 Chevy/GMC Truck
3. A/C Blower Motor Relay - 1967-72 Chevy/GMC Truck
4. A/C Heater Blower Speed Resistor - 1967-72 Chevy/GMC Truck

[LCato]

Thanks for the response and guidance Richard. Guess I'll jump in!

[Rich72C10]

NP, A/C trucks are tight under the dash. Now just to add, I had already been in my dash a number of times and I had already replaced all my hoses when I put in my radio and had my cluster out to update it to tach. I had also played with the A/C Heater controller to replace its light bulbs with LEDs.

So by the time I found out that I needed a new Fan switch i was well versed with the dash.

If your hoses are old/brittle - I'd give extra care while you are up under that area.

Oh, the A/C Heater Blower Speed Resistor - not an easy item to replace if I recall correctly - you have to take the glove box paper thing out to get to it. Or at least that is what I did. Getting that glovebox cardboard out takes all kinds of extra care (luckily mine had already been replace before I got the truck).

[LCato]

Thanks again for the help Richard. Your comments gave me the guidance I needed.

Just to close this out for others in the future looking for guidance on this task – below are the steps I followed which took approximately 5 minutes to complete:

1. Remove the two large screws on the bottom edge of the dash that attaches the Temp Control Assembly to the dash.

2. Disconnect the Hose located behind the Temp Control Assembly that leads to the Left Defrost Vent. This will give you more room to position the Assembly.

3. The Fan Switch is attached to the Temp Control Assembly by two screws, but the Ignition Switch under the dash is blocking your access. Push the left side (Ignition side) of the Temp Control Assembly backwards so you can see and removed those two screws. You’ll have to apply constant pressure on the Temp Control Assembly to maintain access to those screws.

4. Replace the defective Switch with your new one and follow previous steps in reverse.