72 E AC fan speed control

It sounds as if it's wired incorrectly at the switch or you have a defective switch, check your schematic. I only have the diagram for the SII, but it should be similar. You can test the switch with a voltmeter. There are four lugs on the switch: I, A, C, D. Disconnect all the leads attached to the switch, and check as follows:

I is the +12V connection. The "A" connection is for low speed. So when the switch is set to low, there should be conductivity between I and A. There should be no connectivity between I and any other lug

With the switch on medium speed, there should be conductivity between I and D. I and A remain connected.

On High, conductivity between I and C. I and A remain connected., I and D may or may not remain connected.

If the switch is in good shape, then make sure the wiring is set up correctly:

The wire to the a/c clutch (B),the wire to the fan (WU), and the wire to the bottom lug of the resistor (U), should be on lug A.

The wire to the top lug of the resistor(N) and the fan motor (R) should be connected to lug C.

The wire to the center tap of the resistor(G) should be connected to lug D.

Your resistor is probably fine. If you can scan the electrical diagram for SIII, send it to me off line, and I'll make sure the above test procedure still works.

Mike Frank

First, questions like this should be posted to the E=type forum, not general discussion.

Second, it sounds like the fan resistor is shot. It's located under the heater box in the engine compartment. It's that long, round tube-like thing with wires attached. New ones are hard to come by. I'd suggest you try the "usual suspects" (XK's Unlimited, SNG Barratt, Terry's, Coventry West).

Steve Weinstein, JTC-NJ
'72 E-type 2+2
'70 XKE FHC