Intermittent climate control

Q I have an intermittent electrical fault with my 2007/8 Ford Ka Style (old shape) 1.3 with airconditioning. Everything usually works fine, but now and again the aircon switch and the recirculating switch do not illuminate or work. This also means that the temperature control valve goes to hot, although the fan still works. If I turn the ignition key off and on two or three times everything works again for the next 25 times.

When the fault occurs it must mean that there is no supply to the aircon switch. It may also be a bad earth connection. Where is the earth point on the left-hand sill on this vehicle? R Banks

A Given that the switch is intermittent in its operation and that the turning off and on of the ignition switch will reset the system and allow it to operate again, I suspect that the climate control panel or its connection is at fault. This is a sealed panel and the first point to check would be the connecting plug.

The 12-pin connecting plug at the back of the panel should be inspected to ensure that all terminals are clean. Remove the connecting plug and spray it with a switch cleaner to ensure good contact is being made. If you can find no problems with the connecting plug, I suspect the control panel is the source of the problem and will need to be replaced.

My wiring diagram shows no earth connection on the left-hand sill. The earth connections should be easily found behind the dash by following the loom back from the aircon.