Electrical Question (Heater/AC Fan)
Thread Starter
Burning Brakes
Joined: Jun 1999
Posts: 751
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From: Chandler AZ
St. Jude Contributor
Electrical Question (Heater/AC Fan)
Hi,
I am having to hook up some of my Heater/AC control wires but my Haynes, Factory Assembly manual schematics are not very clear. I need some help from you if you can please.
What color wire is directly connected to the heater/AC blower motor fan? I know its either Orange or Purple from several schematics but its not clear. Its a 1971 LS5.
Is it this one from the main harness from the drivers side? If not what does this one get connected to?
Or is it from this cable I removed?
Because of the connector type on this cable (does this cable have a name?) I can either connected it to the motor (same connecter as top pic Female which mated to the male motor spade) or to a purple wire Female that looks like that also could connect to the fan blower motor.
I believe there was a factory "cut" on the orange wire for AC equipped cars as shown below from the factory assembly manual. It looks like the purple wire is connected to the blower motor. If so how does the wire assembly above get used?
Thanks in advance for your help and Merry Christmas
I am having to hook up some of my Heater/AC control wires but my Haynes, Factory Assembly manual schematics are not very clear. I need some help from you if you can please.
What color wire is directly connected to the heater/AC blower motor fan? I know its either Orange or Purple from several schematics but its not clear. Its a 1971 LS5.
Is it this one from the main harness from the drivers side? If not what does this one get connected to?
Or is it from this cable I removed?
Because of the connector type on this cable (does this cable have a name?) I can either connected it to the motor (same connecter as top pic Female which mated to the male motor spade) or to a purple wire Female that looks like that also could connect to the fan blower motor.
I believe there was a factory "cut" on the orange wire for AC equipped cars as shown below from the factory assembly manual. It looks like the purple wire is connected to the blower motor. If so how does the wire assembly above get used?
Thanks in advance for your help and Merry Christmas
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,599
Likes: 7,046
From: New Or-leens Loo-z-anna
Connect a voltmeter to the orange wire with the key OFF---turn the key to the ON position---Is there any voltage?
If not.......turn the blower switch on----any voltage now?
If so, it could be the blower supply wire.
Maybe the black wire with the in-line condenser is to prevent radio static on the ground connector?
If not.......turn the blower switch on----any voltage now?
If so, it could be the blower supply wire.
Maybe the black wire with the in-line condenser is to prevent radio static on the ground connector?
Melting Slicks
Joined: Mar 2005
Posts: 2,095
Likes: 299
From: Midlothian VA
Believe the orange blower power line is part of the main ignition harness intended for non-A/C cars.
The purple line is part of the separate A/C harness.
The purple power line is used on A/C equipped cars.
The purple line comes off the A/C relay & blower resistor.
It then connects to the black leader with the noise suppressor in your second photo.
The black leader then connects to the blower positive/hot terminal.
Notice in your AIM the orange connector is cut off & the black ground wrapped with it is used (ground). The purple is then connected to the motor though the A/C harness should have provision for a separate ground wire.
I'd simply ignore the orange connector vs cutting it off.
Are you installing a replacement harness or is that the original?
The purple line is part of the separate A/C harness.
The purple power line is used on A/C equipped cars.
The purple line comes off the A/C relay & blower resistor.
It then connects to the black leader with the noise suppressor in your second photo.
The black leader then connects to the blower positive/hot terminal.
Notice in your AIM the orange connector is cut off & the black ground wrapped with it is used (ground). The purple is then connected to the motor though the A/C harness should have provision for a separate ground wire.
I'd simply ignore the orange connector vs cutting it off.
Are you installing a replacement harness or is that the original?
Last edited by Hammerhead Fred; Dec 24, 2013 at 08:10 AM.
Thread Starter
Burning Brakes
Joined: Jun 1999
Posts: 751
Likes: 0
From: Chandler AZ
St. Jude Contributor
Fred I think your right on spot here. The wire harness is new and I have been wrapped up in engine work and had disconnected the wires quite a long time ago. I have not used the Orange wire but am using the GND wire from that harness to the GND lug on the motor. Then using the Purple wire as described above by you to control the fan. Looks right. Will check it when I bring power to the system some time in the distant future 
Thanks again for helping me think through this.
Thanks again for helping me think through this.
Former Vendor
Joined: Aug 2006
Posts: 76,656
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
On a/c cars you don't use the Orange wire.. you use the AC jumper harness that comes out of the console of the car.
The black wire is the noise capacitor.. you plug this into the motor, and then into the factory ac harness. You can't miss it either, there is only one plug on the a/c harness it will plug in to.
In this picture you can see where the a/c harness routed through the firewall...
The black wire is the noise capacitor.. you plug this into the motor, and then into the factory ac harness. You can't miss it either, there is only one plug on the a/c harness it will plug in to.
In this picture you can see where the a/c harness routed through the firewall...
Last edited by Willcox Corvette; Dec 25, 2013 at 10:34 PM.
