Derrick Reynolds

I have a '70 vert with BB and AC. When I got it, I couldn't get the blower motor to go no matter what I did. After reading literally dozens of blower motor threads here, and trying to follow the advice, I found that the HVAC harness was so boogered that I felt I was wasting my time. I ordered a new harness from Lectric Limited, and installed it recently. I still can't get the blower motor to go, and I can't find anything clear to help me diagnose the problem. Any help here?

I remember a thread a long time ago that was clear on which wire was which speed etc, but for the life of me, can't find it now.

0Willcox Corvette

First I would jumper 12 volts to the purple wire connection on the blower motor and make sure the motor is functioning. If it blows great we move on...If it fails then jumper a new ground from the blower motor to the engine and try again.

Once you have established the blower is good then I would double check the fuse. But don't test the fuse, test on the terminal connectors in the fuse panel. A fuse can be good and still not pass continuity to the terminal if there is corrosion in the fuse panel.

Once you have established power on the "other" side of the fuse (brown wire).... I'd then move back out to the engine side and pull the connector from the resistor on top and with the blower in any position but hi I would check for voltage on either Yellow, Light blue or green. depending on which speed you have the blower switch on inside the car.

If you have power at the resistor then I would take a hard look at the relay on the firewall and the connectors attached to it.

If you have no power there then I would go inside the console and start testing the blower switch.

Also note: The orange wire on the firewall has a standard fuse in there but if this is blown it will only knock out hi blow and not the lower speeds.



Here is how to test the blower switch in the control.



Willcox

Derrick Reynolds

Willcox:

Thanks for posting that. And thanks for squaring me away on the headlight actuator switch, it is installed now and working correctly.

For those not in the know, I bought a headlight actuator switch from Willcox, and upon attempted installation, the thing broke in my hand. The manufacturer failed to do the right thing, but Willcox sent me a new one at no charge. This is another reason why they are my preferred vendor!

Anyway, I think I am having a hard time comparing the diagrams to what is in my car. But some sleuthing has resulted in the following observations:

1. The darker of the two blue wires (I think that is the D BL in the diagram) appears to be hot regardless of the position of the fan switch.

2. As is, all other wires are not hot regardless of the position of the fan switch.

3. I jumped the light brown (maybe the "tan" wire in the diagram?) to the positive battery terminal, and the blower motor runs in the first 3 speeds, but not in "max".

4. The connector that has the light brown and black wires that is supposed to connect to the underside of the switch is not hot at any time.

So, comparing tonight's sleuthing results to your analysis, I think I have confirmed that the blower motor is functioning.

I will test the fuses in the fuse panel next. After that, I get a little fuzzy, but I will look at it more.

Thanks again.

PK

Derrick Reynolds

OK, tonight's progress:

I checked the fuse, and it was blown. This gave me pause, and caused me to re-analyze what I can not reconcile to the wiring diagram I have in the AIM, nor what Willcox has posted. Let me try this:



It is hard to see in the picture, but I tried several times, and this is the best one I got. The connector that comes out of the HVAC switch just has the brown (tan?) wire. The connector that goes to it has a brown (tan?) wire AND a black wire. I cannot find this black wire on any of the wiring diagrams I have, nor on the Willcox one posted here. Since the tan wire is supposed to be a hot wire, with the fuse out of the panel, I tested the connector with the tan and black wire for connectivity to ground. There was connectivity, but not good, about 2000 ohms to ground. Does anyone know what this black wire is?

0Willcox Corvette

The black wire is the ground for the control, you can see the terminal in your picture. I revised the picture above to indicate the double ground on the side of the control. I also discovered one wire color (running to the blower switch) was colored wrong so I revised this too. If you saved a copy of the picture above delete it and re-save the one at this link, it is 100 percent correct.

http://repairs.willcoxcorvette.com/1...function-test/

That tan wire isn't the power wire to the blower, I'll have to look at a schematic and see which wire that is.

The brown wire at the control switch is the power input.

Derrick Reynolds

I'm sorry, but I am still confused. I think I have the one on the left in this picture correct:



But the other one in this picture, doesn't seem to match the schematic:



That brown wire on the right goes to the connector in my hand. When I took it apart, the connector with the brown and black wire shown in the first picture was connected to the connector in my hand. Is that right?

Also, do you know the correct amperage for the AC fuse at the fuse box? The one I took out is so worn, I can't read the numbers.

Thanks for the continued help. I openly admit that electricals are the weakest part of my car knowledge!

0Willcox Corvette

Okay.. that's correct.. I couldn't tell.. but that should be your 12 volt input from the fuse panel.

0Willcox Corvette

I missed the amp question, it's 10 Amp on the heater and re-check the picture, there was an error on one wire... I changed this about two hours ago...

Derrick Reynolds

10 amp for a car with AC? It looks like a thick one, 25 or 30 amp.

Derrick Reynolds

That is what I was thinking it was too, but it has a ground wire in with it. It is a brown wire AND a black wire. I can't find that black wire on any of the wiring diagrams either. Looks like a short circuit to me.

0Willcox Corvette

I'm going nuts... 25A. I'm sorry.. I pulled a fuse panel pic and looked at the gauges fuse for some reason.



The connector C that has two black wires in it... they are grounds.

Derrick Reynolds

This was great on many levels, and we are making progress. However, you mashed two pictures together here, and the connector you labeled "A" in one picture is the same connector that you labeled "B" in the other. There is another connector with two black wires that wasn't visible in the prior pictures, so I put things back together the way they were when I took them apart, and it looks like this:



You can see in the photo that I have connected the two black wire connector to the ground tab as instructed in your photo to connection "D". This is consistent with your wiring diagram.

When I took the switch apart, the connector that is labeled "A" in one picture, and "B" in the other was connected to the connector you labeled "C". I have replaced it that way in the photo. Connector "C" still has a brown wire AND a black wire, which is not consistent with any of the wiring diagrams I have seen, and causes me concern that this may be a ground wire ganged with a hot wire.

Also, I still can not get the blower motor to go on the "Hi" setting, even though I checked the fuse in the orange wire, and it is good. This wire was part of the new harness, and the fuse is brand new as well. Any guidance there would be greatly appreciated!

Thanks!

PK

Big2Bird

If it works in all but high, check the high speed relay.

0Willcox Corvette

I must have been in space yesterday because I thought you said the double wire connector wires I labeled C were black... then I re-read it and uggg... I'm glad you didn't hook that to your ground terminal I'd be burning your car up. I see your double black ground on the ground clip in your last picture.

If you have the lower speeds now, move to the relay and work backwards.
Check the orange wire connection at the relay.
Power to the relay comes in on the darker blue wire, which powers up the relay and puts current from the orange out to the blower motor.

Derrick Reynolds

Will do, thanks!

No problem in the double black. I am terrible with electricals, but I do have a multimeter, and check for grounds before I hook anything up to what I think is a hot wire.

This is what worries me, the extra black wire on the connector that you labeled "C". This is not on any of the wiring diagrams I have, nor on the ones you have posted here. I can't help but suspect that this wire was the problem all along, a stray ground that some Bubba added that caused a short, and burned the fuse that I just changed. Since I have already hooked it up this way, I am willing to put power to it and see if the $0.75 fuse blows again, but if someone knows what is going on there I would feel better.

0Willcox Corvette

I don't know... I may have a dash harness in stock and just pull it and take a look. If I don't I have a 72 ac car I can pull the console out of if needed...

I've got a tester here that I can put a signal on the wire and then just follow it down the harness. Works great for finding breaks or shorts.

Willcox

Derrick Reynolds

Awesome, and informative again. Sorry I got distracted, but this is the picture I took tonight"



It looks very much like yours, except that I have an empty terminal next to the black wire. Could it be I have the wrong relay? Should I try connecting the black ground wire to the other terminal?

Thanks,
PK

0Willcox Corvette

I can't see the bottom... but it should look like this.

Should be as marked in the picture above left. Purple, Blue and Orange, with black ground going to the single terminal.



and if it isn't like this one then Go to your local parts store and get a R367 relay That is the BWG (borg) part number that most after market stores can cross.

Willcox

Derrick Reynolds

It looks like that, except that it has two spades on the ground side instead of just one. It also looks crusty and really old. I will see if the local auto parts store is open today, and pick one up.

Thanks!

Derrick Reynolds

OK, the local auto parts store didn't have the Borg Warner relay, or an equivalent. Said they could get one in 2-3 days. So I went back to the garage to play. With the switch set to "max", if I jumped the purple wire to ground, the blower motor came on max. Does this mean the relay is bad?