Quote Originally Posted by Spel1 View Post
There is one other switch that controls the aircon fans - the temperature one on the thermostat housing. Have you tried closing that circuit or changing the switch to see what happens? Standard switch is meant as an overheating protection at 100 degrees I think. I have replaced that unit with a 90 degree one to control my second electric fan (my 91 has AU Falcon fans, fan 1 controlled by TM4 at 89 degrees, fan 2 by that switch, means both fans don't blast off at once and temperature is more stable. Fan 2 also comes on when I have the aircon running, I have removed the front fans as fan 2 by itself is more efficient). Anyway, with that, this simple switch has a lot to do with the AC circuit, if it's faulty the AC fans won't work, no fans no AC. Sorry if you have covered this already, haven't scoured the thread that carefully.
You may well be right about that. The wires to that switch (I thought it was just a sensor) are disconnected from it due to the contact tabs being broken off. It does not really explain why the aircon fans come on intermittently.

Since I changed the slider switch the other day, I can now get the aircon fans to work again but not the heater fan and therefore no heat in the cabin

Coopers quoted $3 grand to fix it and wanted the car for a week. That is just not an option for me so I guess I'll just keep driving our members mad and/or experimenting. For a start, I'll take your advice and change that switch -not for the first time - I changed it a year or so ago and the contacts on the new one broke off too.