blower circuit help.

[no1udknow]

Hey guys. On my 68 I am only getting 6-7 vdc to the switch on the blower controls and the same at the motor. Does the power go through a relay or something before reaching the switch? I powered the blower fan direct and it works fine, but with only 6-7v it will not turn. If I need to run a new power line direct to the controls I will but I couldn't find a definitive wiri g diagram in my googling

[ray_mcavoy]

The switch should be receiving full battery voltage on the brown wire. It sounds like you have a bad connection somewhere.

Starting at the ignition switch, a 12ga brown wire runs from the ACC terminal to a bus bar in the fuse box that powers 3 or 4 fuses. One of them being the HEAT / AIR COND fuse. From there, a 14ga brown wire runs to the blower fan switch. I believe trucks with AC have an added inline connector in this wire shortly before it reaches the switch.

I'd recommend that you start by checking the HEAT / AIR COND fuse to make sure it is making good contact with the clips in the fusebox. And check the fuse clips for any signs of rust/corrosion. Also check the voltage there at the fuse to make sure it is receiving full power from the ignition switch.

[no1udknow]

Originally Posted by ray_mcavoy

The switch should be receiving full battery voltage on the brown wire. It sounds like you have a bad connection somewhere.

Starting at the ignition switch, a 12ga brown wire runs from the ACC terminal to a bus bar in the fuse box that powers 3 or 4 fuses. One of them being the HEAT / AIR COND fuse. From there, a 14ga brown wire runs to the blower fan switch. I believe trucks with AC have an added inline connector in this wire shortly before it reaches the switch.

I'd recommend that you start by checking the HEAT / AIR COND fuse to make sure it is making good contact with the clips in the fusebox. And check the fuse clips for any signs of rust/corrosion. Also check the voltage there at the fuse to make sure it is receiving full power from the ignition switch.

so, I figured it out. Had corroded connections at the fues box, the plug above the key switch, and in the fan switch itself, every time I cleaned one the voltage got a little better lol. The fan switch was pretty bad, I pried open the 3 little tabs that held on the backing plate and then cleaned the contacts on the back plate, and the copper sliding contact with some emery cloth and it came to life. Then I moved on to the wipers, and same thing, corroded connections... this harness looks pretty bad, I think down the line I'd like to get a replacement.