Ya I removed that valve completely and plugged the vacuum line for it just to eliminate that as a possibility. I think that i'm going to have to take the heater box apart to find out.
A relay will give the device (motor) full power form your new hot wire of bigger size that you stock harness will. You will need a excite wire run to the relay to turn on the coil so that power from your new wire can flow to it. Your excite wire would be your old power wire and will only need a trickle of power to activate the really. Using your old power wire will allow it to turn on and off just like it does now with out the added strain on you trucks harness. Have you ever seen someone install a set of good offroad lights and they are not very bright or dim in and out? No really in the line to power them. Most better lights will come with a relay and harness to avoid one, the dimming in and out, and two, overloading your stock wiring. This explains it real good. http://www.bcae1.com/relays.htm
Hooking up a relay is cake-walk... it's hooking up the relay to get full power on "HI" while still allowing settings for Low and Mid.
I have been emailing the guy I know who did the Grand Wagoneer mod trying to figure out what he did to wire in the relay and from what I am getting out of him it sounds like he just has OFF and FULL BLAST with no low or mid.
I've done the headlight upgrade to using relays and heavier wire, a definite improvement.
But I slill can't get it clear in my mind if doing a relay on the blower motor will just give me full power or no power. It would be nice to have the different fan speeds just in case It works really well.
Here's another question if anyone knows. I took the heater box cover off this morning and found that the previous owner had cut the green wire coming off the A/C Evaporator Thermocoupler terminal and no other wire was anywhere to be seen. The Themocouplers other terminal had no wire attached to it at all with no wires for it anywhere in site.
What he did was cut the wire from the high setting on the fan switch. He used the wire from the high setting on the fan switch to actuate the relay.
He still has low and mid settings from the existing wire harness, the only change is using the high setting to close the relay and allow full voltage to the blower.
The power wire from the new Relay would have to tie in to the existing wire that powers the fan motor, but the way you described it it sounds like it will work, I was thinking that 2 power wires would be a conflict but the more I think about it it makes sense.
Maybe I'm overthinking it, woundn't be the first time.
Thanks guy"s for all the good advice!
Now I just need to figure out how to wire my A/C Thermocoupler
The power wire from the new Relay would have to tie in to the existing wire that powers the fan motor, but the way you described it it sounds like it will work, I was thinking that 2 power wires would be a conflict but the more I think about it it makes sense.
Maybe I'm overthinking it, woundn't be the first time.
Thanks guy"s for all the good advice!
Now I just need to figure out how to wire my A/C Thermocoupler
That's right. The power wire from the relay splices into the existing power wire for the blower. With this setup, there will be no power to the blower through the existing wire harness with the switch on high (as you've cut the wire from the high fan position to use in activating the relay).
I haven't done this upgrade yet, but I plan on it prior to winter.
Thanks for trying with the wiring diagram Josh.
And thanks Jason for clearing that up, I'm ready to tackle it now, just have to start ordering parts now. I'll post an let everyone know how it works out.
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1974 F100 Custom Styleside 428 Cobra Jet Dual Quad
