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.

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

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

Fuse panel incase im missing any fuses

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[YakkoWarner]

No power on the purple wire means something upstream from there is dead. If all fuses are in fact good, I'd start looking at the blower switch assembly. If the old motor doesn't run with 12V applied, then there is a chance too much current got pulled and did some thermal damage.

 

[chappys4life]

T

No power on the purple wire means something upstream from there is dead. If all fuses are in fact good, I'd start looking at the blower switch assembly. If the old motor doesn't run with 12V applied, then there is a chance too much current got pulled and did some thermal damage.

thank you. I am suspecting the same thing. Just went through the wire harness from the 12v block on the firewall and peeled back the old tape to check all the wires for shorts or cuts. It was all clean. Also cleaned up the factory ground on the firewall just to be safe.

Still have a clean ground from the factory and additional wire. I checked voltage on the plug going into the resistor and not a single lead had any voltage no matter the switch setting. I also went through again and checked the fuses. The only one that was suspicious was the very top 20 amp but still read fine on the meter, instill replaced it. One side looked like it wanted to short it was black.

I have the dash pad off. Thinking I’m going to pull the gauge cluster and start testing. The plugs that go into the control panel what should they be reading? I assume one of the 4 pins on the switch has to be 12v

 

[Edelbrock]

This isn't really the answer you were looking for, but it would be a temporary workaround.

 

[Jgonick]

I checked voltage on the plug going into the resistor and not a single lead had any voltage no matter the switch setting

I believe you should have power on the yellow wire at the resistor (all the time) once the key is turned to run position. That is why the blower runs all the time on the older squares bodies. I would check for power on the yellow & brown wires on the selection switch next. Also the fuse you mention- is very suspicious-That is the one that feeds your A/C- Definitely make sure it has power there and making good contact with the fuse (should be 25 amp).

Attaching wiring diagram in case you need it.

 

[Ditch Wicked]

I was having a similar problem with the blower on my HVAC also. Took the Burb to my Mechanic to do an inspection. Turns out the plug to the blower on the firewall wasnt pushed all the way on. My mech just gave it a little push, and now my blower works. Sometimes its the simplest thing.

 

[AuroraGirl]

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.

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

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

Fuse panel incase im missing any fuses

You must be registered for see images attach

IM glad I read your post, I just found out about the gmt400 fan upgrade from it

I have a 1996 c1500 im parting out, im taking the fan for the square

 

[chappys4life]

As the plot thickens finally making some progress. 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.

 

[Jgonick]

I install the fuse it is very loose

This could cause heat build up- on the loose side squeeze the connector to make it tighter. The thick orange wire is coming from the Ignition Switch. When you jump something directly to the battery you are removing the safety feature of the fuse- If you aren't careful you will cause damage.

 

[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.