Help with power to blower motor switch

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Help with power to blower motor switch

Postby kgroombr » Sat Dec 29, 2012 1:57 pm

My blower motor on my 77 Vega with A/C stopped working.

Trouble shooting so far determined fuse is good and is getting power. I am getting no power at the switch socket. I am unable to find a wiring diagram for the A/C version of a 77 Vega, but I checked all pins at the socket and all read zero (Ignition switch is on the entire time while checking).

I am guessing that the wire supplying power will be the same color as the non-A/C version (brown), but don't want to waste a bunch of time tracing the wrong wire (plus a couple wires on this look brown to me as one is just darker than the other).

Does anybody know which wire supplies power to the switch and what may be the cause of power not making it to the switch (all other items in the dash are working fine).

Thanks,
Ken

blowermotorclip1.jpg

blowermotorclip2.jpg
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Re: Help with power to blower motor switch

Postby spencerforhire » Sat Dec 29, 2012 4:50 pm

I don't think I have a diagram for an A/C H-boby, but off the top of my head it's possible that the fan speed control switches ground and not power like some other GM vehicles. Normally the fan power from the fuse is an orange 14 or 16 gauge wire; have a look out under the hood where there's a couple of relays on the A/C box near the fan motor.
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Re: Help with power to blower motor switch

Postby kgroombr » Sat Dec 29, 2012 5:29 pm

spencerforhire wrote:I don't think I have a diagram for an A/C H-boby, but off the top of my head it's possible that the fan speed control switches ground and not power like some other GM vehicles. Normally the fan power from the fuse is an orange 14 or 16 gauge wire; have a look out under the hood where there's a couple of relays on the A/C box near the fan motor.


Never thought of that. I will check this when it stops raining.

Thanks!
Ken
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Re: Help with power to blower motor switch

Postby stage169 » Sat Dec 29, 2012 7:02 pm

These two pages are from the 1977 Vega & Monza Shop Manual. HV is the Vega. Hopefully these will help. #50 is power and that must be a relay above the 4 wire connector? Maybe you could jumper the two 12ga brown wires there (50B & 50E) and see if it works.

Looks like one wire color is not correct to your connector for the blower switch, yours has a yellow wire and the schematic shows a green light wire. I guess it could of faded but it sure looks yellow in the pic.
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Re: Help with power to blower motor switch

Postby spencerforhire » Sat Dec 29, 2012 8:33 pm

Please disregard my first post; according to the diagram it's wired normally; you should have power on the 12g brown wire at the fan speed switch with the key on. If you don't there's a blown fuse or something wrong with the ignition switch itself. Check all the fuses; the markings on the box can be deceptive. If you can find power on the brown, jump it to the purple and the fan should run. If not your problem is under the hood.
The "fleet"-
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
06 Silverado 2WD ex.cab daily
03 Silverado 2WD ex.cab (retired)
06 Haulin' 20ft enclosed car transporter
06 GMC Canyon Shop truck
07 Colorado project( 5.3 4L60e swap)
99 Saturn SL1- wife's car
01 Saturn SC2- son's project
07 Saturn Ion Redline project
and 4 more Saturn "parts cars"
Note- the very act of listing all of these has made me realize I have some kind of problem.....

Visit http://www.spencerforhire.ca
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Re: Help with power to blower motor switch

Postby Monza Harry » Sat Dec 29, 2012 9:25 pm

As a follow up a problem I had on my old Chev Van was the wiring passing through the fuse panel. My problem was do to corrosion from its proximity to the battery (about 4") on our cars the world famous cowl water leaks could be causing you headaches that took me 3 days to find. Hope this isn't needed, as it was a pain... Harry
I'm not a hoarder I'm a preservationist 78 Monza Spyder (~Soon(ish +/- I guess) To Be 2+2 with Spoilers)
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Re: Help with power to blower motor switch

Postby kgroombr » Sun Dec 30, 2012 10:42 am

spencerforhire wrote:Please disregard my first post; according to the diagram it's wired normally; you should have power on the 12g brown wire at the fan speed switch with the key on. If you don't there's a blown fuse or something wrong with the ignition switch itself. Check all the fuses; the markings on the box can be deceptive. If you can find power on the brown, jump it to the purple and the fan should run. If not your problem is under the hood.


It was a thought and I appreciate the input.

Thanks,
Ken
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Re: Help with power to blower motor switch

Postby kgroombr » Sun Dec 30, 2012 10:44 am

Thanks all for the input and diagram! It isn't raining today, but a bit chilly. I am going out in a bit and start the troubleshooting. Once I find the problem/solution, I will post it.

Thanks again.
Ken
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Re: Help with power to blower motor switch

Postby stage169 » Mon Dec 31, 2012 11:22 pm

Ken good luck troubleshooting! I don't know if this will help but I was looking a little more in the manual so here goes.

The instrument panel feed on the schematic shows 50B and that should have 12vdc if the fuse is good. 50B goes to the 4 pin connector for the Time Delay Relay located on the selector duct assembly. The relay prevents compressor engagement for 2-5 seconds after turning ignition "ON" or placing controls in A/C mode.

You can see that this relay should put power on 50E which allows power to the compressor switch and the fan switch (50C). Anyway if you can find this relay and have power to it and not the fan switch then this spot is where your problem is.

Hope this helps and it is something simple to fix. Brian
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Re: Help with power to blower motor switch

Postby kgroombr » Fri Jan 04, 2013 6:09 pm

This was it. I don't see this on the schematic above, it might be there, but it isn't the easiest schematic I have read, and I know how to read them since I am a electrical engineer. I unplugged this, cleaned the contacts, plugged it back in and all works fine now. I am glad it did work as I wouldn't know where to find this part now.

Thanks a bunch for taking the time to help me (you and everybody else!!)

Ken

stage169 wrote:Ken good luck troubleshooting! I don't know if this will help but I was looking a little more in the manual so here goes.

The instrument panel feed on the schematic shows 50B and that should have 12vdc if the fuse is good. 50B goes to the 4 pin connector for the Time Delay Relay located on the selector duct assembly. The relay prevents compressor engagement for 2-5 seconds after turning ignition "ON" or placing controls in A/C mode.

You can see that this relay should put power on 50E which allows power to the compressor switch and the fan switch (50C). Anyway if you can find this relay and have power to it and not the fan switch then this spot is where your problem is.

Hope this helps and it is something simple to fix. Brian
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Re: Help with power to blower motor switch

Postby stage169 » Wed Jan 09, 2013 8:43 pm

Ken, glad to hear it works now. I can't believe the manual had that little troubleshooting guide and it doesn't even mention the time delay relay. Stay cool :D Brian
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