Blower Motor not working

[chappys4life]

Working on fixing the ac in my 1979 suburban. I just recently picked it up like a week ago. When I got it the ac blew faint but was cold. Now all of a sudden no air output is coming out on ac, vent, or heat.

I figured I do not know the last time any of these parts where touched so did some replacing. So far I have done
- blower motor (gm 15-80213) for a 88 chevy to make it blow better
- blower motor realy ultima ut-rlyu0176
- blower motor switch ac delco 15-71517
- added new 16 gauge ground wire from blower motor to rad support.
- cleaned factory ground wire to firewall

Testing I have done
- checked all of the fuses and no blown fuses.
- purple wire from the relay to the fan motor I get no voltage no mater the switch setting.
- If I jump 12v to the new blower it spins fine.
- Old blower motor does not spin with 12v applied.
- Continuity with meter from ground on blower motor & filter to battery
- checked the plug connected to the resistor. None of the wires have any voltage when the switch is on any setting

Any suggestions on what else to check? Its driving me nuts

Fuse panel incase im missing any fuses

[Richard D]

I don't know how to diagnose electrical problems, but the stock blower motor has a little 90 degree hose to keep the motor cool.

[Dead Parrot]

Check the wiring diagram and verify you have +12V to the input of the switch. Maybe the paperwork with the switch will tell you which is the input.

Pull, visually inspect and re-seat all fuses. They can get corroded in the sockets. While fuses out, check for melted sockets.

[chappys4life]

I removed the fuse panel and it looks like there was a thermal event as the plastic at the fuse block for the ac fuse location is melted. When I install the fuse it is very loose and I have 12v on one leg but not both. When I looked at the back of the factory fuse block I see a thick orange wire feeding the block and then a brown wire for the ac fuse location. I chased that brown wire up to the ac selector switch. It looks like in the ac selector switch gets the 12v then feeds 12v to the brown/white wire. I made a jumper from 12v straight from the battery to the brown wire on the ac selector switch and immediately the blower motor started running. I started the truck and felt air flow. The downside is the alternator harness started smoking.

So forward momentum and backwards at the same time.

[chappys4life]

I did a jumper to test if it worked, should have used a thicker wire. I setup a cole hersee continuous relay feeding a small blue sea fuse panel that turns on from switched ignition. Ran a new 12 gauge wire from the fuse panel to the solid brown wire on the ac selector. We are in business ac & heat work. The relay and little fuse panel have become a common staple in my old junk. Hate drilling the holes to mount them but lets me add fused accessories without killing the old harness.

Plan on saving up for vintage air and a new harness. This is at least a safe fix for now.

[RustyPile]

Originally Posted by chappys4life

I did a jumper to test if it worked, should have used a thicker wire. I setup a cole hersee continuous relay feeding a small blue sea fuse panel that turns on from switched ignition. Ran a new 12 gauge wire from the fuse panel to the solid brown wire on the ac selector. We are in business ac & heat work. The relay and little fuse panel have become a common staple in my old junk. Hate drilling the holes to mount them but lets me add fused accessories without killing the old harness.

Plan on saving up for vintage air and a new harness. This is at least a safe fix for now.

Disconnect the negative battery cable at the battery. Remove the A/C control panel.. You'll see a brown wire that has a plug in it.. That plug, over time, overheats and corrosion sets in. This is a common failure in all GM lines during that model run.. Cut the plug out and splice the two ends together, using a butt splice and solder.. Put everything back together and connect battery cable. Test operation...

[chappys4life]

Originally Posted by RustyPile

Disconnect the negative battery cable at the battery. Remove the A/C control panel.. You'll see a brown wire that has a plug in it.. That plug, over time, overheats and corrosion sets in. This is a common failure in all GM lines during that model run.. Cut the plug out and splice the two ends together, using a butt splice and solder.. Put everything back together and connect battery cable. Test operation...

AC control panel side was fine. It was at the fuse. The fuse was not giving 12v to the brown wire. I think the brass terminal strip got messed up when the fan burned up. I ran a new 12v wire to the brown wire on the ac control panel and now its working.