I read the sticky on modifying the hi speed for the blower. Here's the question..

Couldn't I just mount a relay, run a wire from the battery to the relay and just use the existing wire with at the resistor to trip the relay? It would eliminate having to do anything around the fan switch, just disconnect the green wire(high speed) from the resistor and use that to trigger the new relay.??

Or am I missing something?

 

You're missing the switching through the ignition switch, climate switch, and fan switch. Too simple a setup will back feed and not shut off with the key switch, and maybe some other gremlins also.

I noodled through the diagrams once, and I think I came up with 5 relays to properly control the fan current and protect the switches. Jim Lane's fix covers the most severe switch current issues adequately.

hope it helps

 

sorta.... Isnt the green wire coming from the fan speed switch to the resistor the last stop before the motor?

 

You really want the high speed off of the ignition, meld down is no fun

 

So I did some checking.... Im puzzled a bit...

If I unplug the blower I have 14.3v at the connector for the blower under the hood, when I plug the motor in I get 10.7V, I replaced the motor....no change..

 

its the load your pulling threw the wire, with the factory wire you loose voltage under load, as its to small

 

Right, the motor load really drags down the voltage. Just whipping numbers off for some crappy fuzzy electrical math, this is not going to be dead on as I'm drawing on figures that are not 100% spot on.

I recall Jim Lane amped the motor at around 16 amps, and you're voltage is pushing down around 10.8 from 14.3. so that gives us a voltage loss of about 3.5 volts. So 3.5/16 = 0.219 ohms of resistance in the whole run. Which wouldn't be a problem on say 2 amps which would only drag the voltage down by 0.438 volts, but 16 amps is a whallop. So by reducing the resistance in the supply circuit by say a factor of 10, our voltage drop goes by about as much. down to only 0.350 volts. The easiest way to decrease resistance and up the voltage on a load like the blower is to make a large gauge wire run and keep it short. 12 ga wire has an average resistance of 0.001588 ohms/ft 14 ga wire runs 0.002525 ohms/ft.

And then we can drag into wattage, 10.8v x 16A = 172.8Watts whereas if we can get 14.3V to the motor we get 14.3 x 16A = 228 watts. Which is about 25% more work ^^

Anyway that's the super overcomplicated reason why you're only getting 10.8 volts at the motor, and 14.3 volts when its disconnected, voltage drop is entirely based on the load applied to the circuit and the resistance in the circuit. Jim Lane's fix reduces resistance by alot and that gets us moar cowbell