Blower Motor Trouble

[Jon87V20]

Hi. I recently picked up a 79 GMC Sierra Grande. After getting it home a friend and I started taking off the smog components and AC components. I wasn't paying attention to what I was cutting and I cut out the harness for the AC/Blower. So now I am trying to figure out how to wire the blower motor. It seems as though no matter which way I configure it, even the way it was set up before, the speed switch in the cab has no effect on the blower speed. I'm talking about the resistor connections. Can anyone possibly direct me on which goes where as far as the wires go? Also will the blower still work proporly even though the AC relay is gone? I have looked at various schematics for both AC and non AC but they don't seem to match up. Thanks a bunch, -Jon

[VileZambonie]

That's because they are different. Why did you hack up your harness? You do need the AC relay.

[Jon87V20]

I removed all of the AC components because they were all inoperable and a drag on the motor. With the harness, like I said I wasn't thinking about it before hand. My mistake. So is there no way to set it up so it will work? Or do I have to go get a standard blower setup and a standard slider control?

[VileZambonie]

Just hook it back up the way it was and reinstall the relay. I ran my wiring inside the cab for the heater controls so you can't see them.

[Jon87V20]

So just missing the relay is most likely the problem?

[DnStClr]

It's a good possibility Jon. A new relay doesn't cost very much. $7-$10.

[Jon87V20]

How can I wire it to bypass the relay? I just don't see the need to get a relay to control nothing. There's no longer any AC. What about bridging the two green wires that normally run to the relay?

[VileZambonie]

It's not controlling nothing. The purpose of a relay is to control a high current load utilizing low current.

[Jon87V20]

I understand what a relay does. I'm saying why re-install one when I've removed all of the air conditioning. If the speed control is in fact not operating because of the relays absence there has to be a way to wire around it.

[VileZambonie]

You will have to wire it like a non AC truck and change the resistor assembly. Just follow the wiring diagram. You will also have to change the switch.

[ccz145a]

You will have to wire it like a non AC truck and change the resistor assembly. Just follow the wiring diagram. You will also have to change the switch.

The A/C switch and wiring is not designed to handle the full current at max fan speed, it is about 15A.

[VileZambonie]

That's why he'll have to change the switch and rewire it according to the wiring diagram. The wiring diagram shows the proper gauge wiring (mm sq) and circuit protection.

[hotrod24]

would this help you out any man

[Jon87V20]

Thanks guys, I'm probably going to just go get a regular blower and switch setup. One more question though. Behind the ac box on the firewall is there a going to be a large hole there or will it be the same as a regular blower situation?

[VileZambonie]

There will be a large hole there. Get one of these click or make your own.