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kna4977 · 09-13-2006, 10:29 PM

I just installed factory A/C in a non-factory A/C truck supplementing the original harness with the A/C harness. Everything still works as it should except for the heater fan. I've replaced the control switch and the relay. If the switch is placed at the High setting, the fan blows Low. If it's placed at Off, Low, or Med, the fan blows on High. The new harness has an anti-dieseling harness connector built in, but there is not a relay as the original system didn't have this component.

At this point, I'm not sure what I have done wrong. I do however need a picture of the fuse box in an A/C truck with everything wired correctly, so that I can at least get back to a starting point to try and solve this problem. I cannot find a diagram that is understandable that combines the regular harness and the A/C harness together. In fact all I can find is just the A/C diagram.

Another thing about the A/C diagram is that it wants you to wire the Orange wire into the cig lighter outlet, but if I do that, the fan blows all the time on high as long as the battery is connected, so I have no choice but to wire it to another accessory that turns on with the ignition. Any help or suggestions would be greatly appreciated!

09-13-2006, 10:29 PM	#1
kna4977 Senior Member Join Date: Jul 2006 Location: Midlothian TX Posts: 305	1972 Chevy Truck A/C Fuse Box Wiring? I just installed factory A/C in a non-factory A/C truck supplementing the original harness with the A/C harness. Everything still works as it should except for the heater fan. I've replaced the control switch and the relay. If the switch is placed at the High setting, the fan blows Low. If it's placed at Off, Low, or Med, the fan blows on High. The new harness has an anti-dieseling harness connector built in, but there is not a relay as the original system didn't have this component. At this point, I'm not sure what I have done wrong. I do however need a picture of the fuse box in an A/C truck with everything wired correctly, so that I can at least get back to a starting point to try and solve this problem. I cannot find a diagram that is understandable that combines the regular harness and the A/C harness together. In fact all I can find is just the A/C diagram. Another thing about the A/C diagram is that it wants you to wire the Orange wire into the cig lighter outlet, but if I do that, the fan blows all the time on high as long as the battery is connected, so I have no choice but to wire it to another accessory that turns on with the ignition. Any help or suggestions would be greatly appreciated!