A/C blower motor wiring by-pass. (1 Viewer)

[g-man]

I wired a 12 gauge wire with 30 amp inline fuse to the positive battery terminal. (skip to pg 3 post #57 to find the results of this testing and skip a bunch of rambling)

 

[g-man]

Then routed through the firewall at the passenger side up high...behind the washer bottle.

 

[g-man]

Then went to the dash and pulled the blank farthest to the right. I installed a switch.

 

[g-man]

Then unplugged the stock plug from the blower motor (to the right of my hand.) And ran another 12g red wire from the switch to the blower below the glove box.

 

[g-man]

Notice the stock plug to the right of my hand. I made a jumper that goes from the motor to the stock plug. This feeds ground back to the dash,the fan switch and on to ground. Female connector goes in the motor and male blade goes to the right side of the plug as shown.

 

[g-man]

This bypasses the heater CB. No more tripping. Only downside is I have to remember to turn the switch off or the fan will continue to run as the work around bypassed the ignition. I need to install a relay near the battery and wire it to an ignition wire so it automatically cuts off with the truck key.

 

[g-man]

The nice thing about this set up is that it can be undone...minus the hole I put in the blank. Been running like this for 2 years without issue.

 

[Willard]

A relay would certainly fix the "I forgot to turn off the fan.

This setup could also be ideal when connecting a dual battery setup. If done right, when the ignition is turned off it will go off like any other accessory.
I think I will try this when I setup my dual battery setup this winter.

 

[SteveH]

It would be super easy to pull the 30a fuse and stick an ammeter inline and see what the current draw of your blower is. That might tell you why the CB keeps blowing.

 

[g-man]

It would be super easy to pull the 30a fuse and stick an ammeter inline and see what the current draw of your blower is. That might tell you why the CB keeps blowing.

Blower motor draws 12 amps on high.

 

[SteveH]

Thanks!

 

[OSS]

You're half way there. You can wire it directly through the slider fan speed switch on the dash so you have all fan speeds. High only blows (literally). Also it's a 100% certainty you'll kill the battery one day by forgetting to turn off the fan when the engine is off. Install an ignition controlled relay behind the driver's kick panel. There's a good spot for it. The wire gauge you used looks a bit small. Use 10AWG. The fan will then blow like a jet turbine.

 

[g-man]

You're half way there. You can wire it directly through the slider fan speed switch on the dash so you have all fan speeds. High only blows (literally). Also it's a 100% certainty you'll kill the battery one day by forgetting to turn off the fan when the engine is off. Install an ignition controlled relay behind the driver's kick panel. There's a good spot for it. The wire gauge you used looks a bit small. Use 10AWG. The fan will then blow like a jet turbine.

I do have all the fan speeds but the left position still seems to leave the fan on low. The negative jumper coming off the blower motor feeds back to the switch and then to ground. Not much chance of forgetting to turn it off while on high. The only real scenario where you wouldn't hear it is if left on a low speed and the radio or other ambient noise was covering the sound of the fan. The 12 gauge wire did "up" the performance of the blower motor. yes I could probably just buy a new motor but my work around was less expensive at the time. At this point I'll prob just put a relay in. What
is the best place to tie into an ignition wire? Coil? starter? At the plug at the steering column?

 

[g-man]

Thanks!

I am saying that I tested mine and it was drawing 12 amps on high. I know it's a 30 amp heater CB that is tripping. Since my blower motor isn't pulling that much amps it must be a combined amp overage. Seems logical that anything downstream from the 10A a/c fuse that was pulling too much would blow the 10a fuse. So we can rule that out. Could be the blower motor, heater relay, bad grounds, worn blower resistor, and or worn switch. If you have something positive to contribute that would be great. here's a schematic of the a/c wiring if anyone would like to add to the conversation. "C" at the top of the image is the power coming in from fusable link. the W-B white/black wires at the bottom are ground wires going to ground.

 

[red66toy]

I am saying that I tested mine and it was drawing 12 amps on high. I know it's a 30 amp heater CB that is tripping. Since my blower motor isn't pulling that much amps it must be a combined amp overage. Seems logical that anything downstream from the 10A a/c fuse that was pulling too much would blow the 10a fuse. So we can rule that out. Could be the blower motor, heater relay, bad grounds, worn blower resistor, and or worn switch. If you have something positive to contribute that would be great. here's a schematic of the a/c wiring if anyone would like to add to the conversation. "C" at the top of the image is the power coming in from fusable link. the W-B white/black wires at the bottom are ground wires going to ground.


View attachment 1769675

Start testing all those things! Make sure the AC compressor clutch is only pulling about 4ish amps. Look for crusty wire connections at the CB and the motor. My motor harness terminal was corroded so that was an easy fix. On high the blower motor does not use the blower resistor so that is not the issue. Focus on making sure grounds are clean and the CB/Motor components.

 

[g-man]

Good call on it not being the resistor.

I just found this info on four seasons blowers, basically saying if the blower motor is 1/2 volt or more off from supply voltage while on high then there are issues with the wiring, switches, grounds etc in the circuit and it's not the blower. I did this test with my simple circuit from battery to switch to blower. It's 3 volts lower than regulator voltage. So there is a problem that is NOT the blower motor. I did notice my wires are warm to hot at the blower.

Here is there info: http://www.4s.com/media/4916184/4S413-Defective-Motor-Or-Not.pdf

 

[OSS]

What is the best place to tie into an ignition wire?

The easiest (and maybe the best) way I found to get an ignition key + signal is to tap into the back of the fuse panel block. I think I used the Engine fuse circuit, but it's easy to find out which fuse gets juice when the key is rotated to ON by using a voltmeter.

Remove the fuse block panel by unscrewing those two bolts and wiggling it out of there. Pushing it in. You need to be able to get access to the rear of the panel.
Next you need to extract the metal contact pin on the circuit you're going to use by unlocking the tiny plastic lock tabs inside the plastic housing that's holding the pin in place. I used a jeweler's eyeglass screwdriver. It needs to be very slender to fit in there. Or maybe I used a smashed paper clip made flatter w a hammer.

Once the plastic lock retainers are taken care of, the metal pin (with attached wire) slides out of the housing. Then just solder a wire to it. There's plenty of room to solder on the pin and the pin will still slide back into the housing and lock on those plastic lock tab gremlins.
Works really well.
Behind the driver's kick panel there is a vacant threaded hole. Your relay in a socket mount can be secured using a bolt in that handy hole.

 

[cps432]

Copper wires eventually get oxygen inside of them and corrode unless they're sealed up like high end instrument cables/audio/computer. I bet you have some wires that are not running efficiently enough for what you're asking them to do. Probably all of us.

 

[g-man]

The problem is finding those wires. I'll try bypassing the ground wires. I'll disconnect the ground wire at the motor and run a temp ground wire from blower to the switch. Then I will voltage test again. Then i'll run a temp wire from switch to ground and test. If neither of these shows improvement I may need to pull the switch and continuity test it.

 

[g-man]

My voltage at the blower motor is 10.73 and the voltage at the battery is 13.80 with the truck running and blower on high. Pulled the ground wire (heavy white w/black stripe) from the blower switch connector plug (switch still in play) and clipped jumper wire to the flat blade then to 10mm ground screw under the dash. Voltage stayed the same on the blower. Then replacing the ground wire to the plug and pulling the large blue and black wire from the plug (high setting wire) and running a jumper from that back to the ground side of the blower..voltage only rises to 10.84 still lots of heat on the ground wires.

Then I pulled the switch to ohm test but before doing so ran the jumper wire from ground side of the blower motor to ground under the dash. Jumped to 12.51 volts!!! And seems to be pushing even more air. Next I will ohm test the switch.