Blower motor / fan switch high current bypass (critique my wiring diagrams)

[bfabian76]

@bfabian76

Yes, still working perfectly.

Not sure if this thread captures it but I was still having some overheating wire issues. I finally went after looking for voltage drops. Turns out, the last leg of the +12v wire to the fan was pretty corroded. I replaced all of the +12v wire with 10 gauge from the battery to the fan. Problem 100% solved. Everything stays cool. Even ran the AC for 1hr in 90 degree Houston weather and all relays were still cool to the touch

Nice. I just did my blower and all of that. but im having some weird issue where it will blow fine, then stop. then start.... it will do that my whole drive. im thinking something is shorting out or melted. havent pulled it apart yet

 

[bfabian76]

What gauge wire did you use for everything else?

 

[TrueTexas]

@bfabian76 Here is the wiring I used

I used 10 Gauge 100% pure Oxygen Free Copper GXL for the entire 12v+ run and last leg of ground to blower motor

I used 12 Gauge 100% pure Oxygen Free Copper GXL for the wiring from control panel to blower motor resistor and the grounds to relay

The key is to make sure your crimps are good. When I fist built the harness, I was still having overheating issues. So I ended up building a second setup with better relays. As it turned out my main issue was the wiring from the 12v+ relay behind the glove box to the blower motor itesef. That wire was so bad, the new Mopar blower motor was pulling ~23 amps. Once replaced, it is pulling 13 amps and the wires all remain cool. Would be good to do a voltage drop test along the path to see where the problem was occurring.

 

[SlipJoint]

After years of replacing switches, resistor blocks, blower motor, and burnt connectors. I am currently starting this project on my 2000 TJ.
All of my wiring for the blower control are burnt (except the small blend door wiring).
I'm having one issue I am confused about at the moment on the 3 wires that plug into the selector switch. I know 1 wire is the LG trigger, 1 wire goes to Pin # 5 of the fan-speed switch, and I think the other is a black wire. My question is which wire goes to which of the 3 pins? Any help would be greatly appriciated.

 

[KingCarGuyZ]

Just finished this install. need to run by and get some bolts to brace the relays up, but already pleased with the reduction in current at the switch. It is crucial that you remember to connect the Black/Tan 12 gauge wire from the blower motor to the loom and the resistor, and not just leave the blower motor floating off the circuit and spend hours wondering why the fan won't work

 

[TrueTexas]

Just finished this install. need to run by and get some bolts to brace the relays up, but already pleased with the reduction in current at the switch. It is crucial that you remember to connect the Black/Tan 12 gauge wire from the blower motor to the loom and the resistor, and not just leave the blower motor floating off the circuit and spend hours wondering why the fan won't work

It's been a while but yeah, if you don't connect the blower ground, nothing works.

I ended up completely replacing both the fan ground and 12v+. Turned out those wires were the worst offenders in my system. I actually rewired the entire 12v+ from the battery with a new fuse / fuse holder and 10 gauge wire to the relay, then ultimately to the blower.

IIRC - after i was done, the fan only pulls about 10-12 amps now. Down from 23 with the vad wiring

Been working great for the last couple of years.

 

[KingCarGuyZ]

It's been a while but yeah, if you don't connect the blower ground, nothing works.

I ended up completely replacing both the fan ground and 12v+. Turned out those wires were the worst offenders in my system. I actually rewired the entire 12v+ from the battery with a new fuse / fuse holder and 10 gauge wire to the relay, then ultimately to the blower.

IIRC - after i was done, the fan only pulls about 10-12 amps now. Down from 23 with the vad wiring

Been working great for the last couple of years.

Your diagram is right, just the loose but with the wire crimpers that’s the problem 😁