Aircon failure

Q The aircon has not been working on my 2001 Ford Focus 1.6 LX since a recent MOT when the garage changed the brake fluid and coolant. On fan speed 1, the fan motor doesn’t run but the aircon switch lights up; on fan speeds 2, 3 and 4, the fan runs, but the aircon switch doesn’t light up. A local aircon service garage suggested I change the fan switch, which I did using a genuine Ford switch, but the fault remains. John Gravestock

A As you have already replaced the fan switch, this leaves a couple of possibilities, but it’s unlikely that either of them would be related to the coolant and brake fluid change.

The first is that the problem is with the heater blower resistor or a poor connection between the resistor and connecting plug. The connection can be checked by unplugging the unit, which is found under the passenger footwell on the side of the heater unit.

It’s also possible that the connections in the fusebox have become corroded. By unplugging the connections and cleaning them using a switch cleaning spray, it may be possible to restore them.

Finally, there's one problem that may have occurred as a result of the work carried out by the garage. If the airconditioning pipes had been disturbed and were in poor condition, it’s possible that aircon gas leaked out and lowered the pressure in the system, which would prevent the aircon from working. However, as you have already been to your local AC specialist, I would have expected them to check the pressure, thus eliminating this possibility.