First post - but only because this forum is AWESOME and I can find nearly anything from the experience of others. Thanks C3 Owners!

My issue - I have had problems with my blower and wipers ever since I dropped my rebuilt 350 into the car as part of my restoration. The blower will not operate from the switch on the center console. Originally, I had bubba'd up things by accidentally putting my ground on the battery terminal on the starter when hooking it up. Fortunately, i had a buddy standing by when I hooked up the battery and he alerted me that I was frying the wiper ground wire - i disconnected quickly and then spliced in a new wire. Later, while doing an interior restoration I discovered the switch ground was burnt - the one that connects to the side of the control head and replaced it as well.

I have read DOZENS and DOZENS of threads on the topic of blower wiring and grounds so I initially believed I had the infamous starter wiring ground problem but have ensured that I have connected it to the Bell housing (2nd bolt since first one has the battery cable bracket). My AIM has the ground on the starter bolt - I've had it in both locations.

I also learned that my blower doesn't look like what is in my AIM nor what I've seen in posts. The noise suppressor is mounted on the top (AIM has it in the interior side) and there is no ground terminal as part of the suppressor connection. But, I did find a spade on the blower housing with no wire so I fashioned a ground wire and connected it to the double connector that is just under the fender - the one that(I think) the wiper ground is connected to. BTW, does anyone know where you can get these little plastic connectors? I don't seem to be able to find them.

Once I thought I had the grounding figured out I connected the battery and tested the blower but still no go. So I created a jumper and ran 12 volts from the battery directly to the power lead of the blower - viola! the blower runs on high. Conclusion, blower works, blower ground is good.

Next, I confirmed continuity on the switch with my voltmeter following the instructions from wilcox - Thanks Wilcox! Conclusion - switch is good.

Next, while sitting in the drivers seat, I jumpered power to all the power leads in the plug that connects to the blower switch. Viola again! Fan runs at all speeds. Conclusion, blower relay and resistor work as they should.

Next, I connect the ground clip from my test light to the switch ground line (the one i had to rebuild) and touch my test light to the battery - it lights. Conclusion, switch ground functions.

Now, I'm working my way back to the fuse block. I had already made a visual inspection of the fuses by adopting the yoga pose I like to call 'the Stingray' by lying on my back with my head under the steering column. I had read that sometimes fuses can lie to you so this time I bring my test light and confirm power on both sides of all of my fuses. Conclusion (I think), power is coming out of the fuse block.

Last test, I use my test light to see if there is power in the switch plug - on the brown wire connector. No Go....

My instinct is to conclude that maybe the spade in the connector is loose/broken/or otherwise messed up, even though it looks good visually. I would hate to think that I have a harness problem - that would really mean trouble.

Does anyone have any additional suggestion? Please let me know if my approach to this is solid.

Thanks, Jerry

 

Jerry,
First off...you are doing GREAT job in finding the problem.

Knowing that the blower motor works when you hot wire it..and also when you add current to the relay and resistors and get all speeds...

I would be using a voltmeter and NOT a test light. A test light will not give you a value of volts. So...even though you get the test light to light up when checking the fuse panel...you can have 12 volts on the outer terminal of the fuse panel...and then...when the fuse contacts this terminal...you can have a voltage drop....and then it can do it again when the fuses touches the inner terminal. SO ..you can start with battery voltage ( 12 volts)...but end up with 5 volts by the time the power makes it to the inner terminal in your fuse panel.

Also...it is always helpful if you can state if your car has A/C or not....due to the wiring is different.

DUB

 

Thanks Dub,

Forgot to mention that this is an A/C car.

I will check the fuse block with my voltmeter and shortly and reply back.

Many thanks!

 

I did the check on the fuse box by climbing under the steering column - i checked them all.

consistent power on both sides of each fuse. 11.74 volts - i suspect my meter might need to be calibrated but since there is no voltage drop at the fuse box it seems like i can start to rule that out....

still... no voltage on the spade with the brown wire that plugs into the blower switch. I think my next step is to remove the spade and see how well the wire is connected - maybe something interesting in there. I can also test the wire itself for voltage. I suspect I only need to depress a tab inside the connector to remove the spade - much like i did on the A/C compressor connector when I rewired it. If anyone has any tricks for this, please share.

I noticed a fairly high volume of reviews on this post - please check my thinking here and let me know if I'm missing something simple.

Have a happy holiday! Jerry

 

further investigation

the wiring diagrams I have in my AIM, along with the one from Lectric Limited, as well as those I've seen circulated here show the Brown wire coming off the fuse box and it goes into something called 'S1' which then powers the brown wire to the blower switch and a purple wire that goes to 'S2'

Also, one of the diagrams shows the brown wire originating from what looks like a block or a terminal before it heads to the switch...

Can anyone shed light on these switches and the terminals.

BTW, the Spade in the switch plug looks like it is in factory condition - well connected and dbl crimped.

Wondering if I should bubba harness this switch wire and splice it into the other brown wire that powers the left side of the control head - the one that plugs in from the bottom... 12 volts are present when the key is on.

Thanks

 

OK...1971 with A/C....got it.

I will bring my wiring schematic home tomorrow and comment on where to check.

On another note....and NOT wanting to come across as if you did NOT check the fuses correctly.....BUT......One side of your fuse panel is 'HOT'as all times....with the key out of the ignition switch. The other side of your fuse panel required the key to be ON in order to check for voltage. The terminals that is closest to the center of fuse panel....and I am NOT talking about the BATT, IGN and ACC ports in the very center. What you want to touch with your volt meter is the metal terminal tang the holds the fuse closest to the center. IF you touch the fuse ....that is NOT confirming that the voltage is actually contacting the metal terminal....where I have has voltage drops due to dirt and corrosion.

If you checked it in this manner ...great.

DUB

 

Dub- I'm heading out but here is the schematic in case you didn't bring one home. I'll check in later tonight and see if there is any progress.



Willcox

 

Thanks for the clarification on the fuse panel. I actually checked both since I knew i only wanted to go down there once.

Thanks for the diagram Wilcox - this is the one I was looking at and trying to figure out what S1 is. Turns out that S1 is the two pronged plug on the bottom of the control head. It plugs into the drivers side of the control head - I haven't figured out what it controls yet since I thought that side was mostly the vacuum port controls.

Anyway, without continuity across this switch, the power lead into the blower switch does not have power. Once I connected it, I had power into the blower switch and confirmed blower across the 3 lower speeds - but nothing on High. I know the Blower is good for this since I was able to get it to work when I jumped it with 12 volts so I know my trouble lies elsewhere in the system. The inline fuse under the drivers fender is good and I will be checking to see if the power side is getting voltage. I suspect the Horn relay is faulty since I don;t have a horn right now... I will look up a few posts on the horn relay.

Thanks

 

confirmed power at the horn relay and through the in-line fuse for the yellow wire...

Checked voltage at the plug going into the blower relay and confirmed voltage on the yellow wire through the plug.

plugged it back in to the relay - firmly... and bingo! high blower!!

Loose connection at the blower relay. Case closed.

On to the wipers and horn.

 

Glad to read that it was a terminal that was loose.

AND...keep that in mind...because that terminal and others carry so many amps when in sue...and the fact that GM had not yet gone to protected circuits that are out in the weather...like that connector to your relay is. The terminals can get dirty and thus cause the system to draw more amps and actually get so hot that the connector melts.

DUB

 

Hello, I was hoping someone could help me figure out why my blower motor isn't working. I have a new harness, motor and switches, but my motor isn't getting power to the orange wire that goes to the motor. I noticed some diagrams show a purple wire going to the blower but mine is orange and I can't figure out why its not working. If I jump 12v to the motor it runs. When I move the blower switch to high I can hear a click but the blower doesn't work. All other speeds i don't hear a click. Thanks in advance for your help. I ran the tests mentioned above but noticed that my blower does not work when I jump power to all the power leads in the plug that connects to the blower switch. I can hear a click noise but no fan when I touch the high speed spade, but nothing in all others