72 Blower Motor INOP
Thread Starter
Racer
Joined: Jun 2009
Posts: 316
Likes: 10
From: Beavercreek Oh
Debaffling this:
The relay is the HI FAN Relay. Sends 12+ direct from the horn relay to the fan motor to protect the switch circuit in the console when running fan on HI. For all lower speeds the switch in the console routes power through the resistor pack then on to the fan. If you have power on Orange & good ground on black at the relay and get no power at the fan/purple then either the relay is bad or your console switch is bad or has no power to it.
You can verify by probing for power at the DBL wire coming into the relay with the switch on HI. You can also verify by probing PPL for lower voltages with the switch on lo/med. No power means your issue is in the console OR your fuse is blown.
The switch depends on the fuse and/or S1 switch feeding it or the switch itself could be mucked up with gunk.
You could also inject +12 at the DBL prong of the relay which should cause the relay to pull in completing the circuit between Orange & Purple. If the fan fires then you know the relay, fan, & grounds are good and you can go dig into the console.
The relay is the HI FAN Relay. Sends 12+ direct from the horn relay to the fan motor to protect the switch circuit in the console when running fan on HI. For all lower speeds the switch in the console routes power through the resistor pack then on to the fan. If you have power on Orange & good ground on black at the relay and get no power at the fan/purple then either the relay is bad or your console switch is bad or has no power to it.
You can verify by probing for power at the DBL wire coming into the relay with the switch on HI. You can also verify by probing PPL for lower voltages with the switch on lo/med. No power means your issue is in the console OR your fuse is blown.
The switch depends on the fuse and/or S1 switch feeding it or the switch itself could be mucked up with gunk.
You could also inject +12 at the DBL prong of the relay which should cause the relay to pull in completing the circuit between Orange & Purple. If the fan fires then you know the relay, fan, & grounds are good and you can go dig into the console.
Melting Slicks
Joined: Mar 2005
Posts: 2,095
Likes: 299
From: Midlothian VA
I confirmed that I have no power to the purple or blue wires at the relay with the fan on high and the selector in all positions but off. In looking at the fuse box I see there is a spot marked ac / heater 25A-confirmed fuse is good as well. I did check the switch prior to installation per Willcox's video on youtube. The switch tested good. I’m baffled here... Maybe I need to dig into the console and verify everything is functioning there. I recall there was another switch on the heater controls. On the schematic above it shows S1 / brown wire goes into this switch first. I'm not sure what this is called but I remember it not being in the best shape when I assembled the console. It looks like it did something with regards to the AC, which is not currently on the car so I figured it wouldn’t cause issues with the blower function.
S1 is tied to the thumb wheel position per the chart above.
It needs to be hot in order to feed the fan switch when the wheel is moved from off to any other setting.
S2 forces low speed fan to run when the left thumb wheel is in any A/C position and the fan switch is set to off - prevents the evaporator from freezing up. If S1 has no power OR doesn't pass power to the fan switch that's your issue. Again, you can test for this by injecting +12 between S1 & the fan switch. If this allows the fan to blow you've isolated and found your problem. S2 only comes into play if you try to run the A/C. The feed into S1 or S1 itself is your likely issue.
Thread Starter
Racer
Joined: Jun 2009
Posts: 316
Likes: 10
From: Beavercreek Oh
There are two switches S1 & S2 feeding the fan switch.
S1 is tied to the thumb wheel position per the chart above.
It needs to be hot in order to feed the fan switch when the wheel is moved from off to any other setting.
S2 forces low speed fan to run when the left thumb wheel is in any A/C position and the fan switch is set to off - prevents the evaporator from freezing up. If S1 has no power OR doesn't pass power to the fan switch that's your issue. Again, you can test for this by injecting +12 between S1 & the fan switch. If this allows the fan to blow you've isolated and found your problem. S2 only comes into play if you try to run the A/C. The feed into S1 or S1 itself is your likely issue.
S1 is tied to the thumb wheel position per the chart above.
It needs to be hot in order to feed the fan switch when the wheel is moved from off to any other setting.
S2 forces low speed fan to run when the left thumb wheel is in any A/C position and the fan switch is set to off - prevents the evaporator from freezing up. If S1 has no power OR doesn't pass power to the fan switch that's your issue. Again, you can test for this by injecting +12 between S1 & the fan switch. If this allows the fan to blow you've isolated and found your problem. S2 only comes into play if you try to run the A/C. The feed into S1 or S1 itself is your likely issue.
Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
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