My Citroen ZX cooling fan doesn't work. The temperature is normally fine without it but when stopped in traffic the engine temperature rapidly comes up and we have to use the cabin heaters to cool the engine instead. Have narrowed this down to a non-operating cooling fan/circuit. Unfortunately have tried everything in the Haynes manual to identify the fault and I can't work it out. The fan works when connected directly to the battery. Battery voltage is getting to the automatic switch (located at the radiator). Bridging the switch connections doesn't make the fan ccome on, indicating that the switch is ok. Earth connection has been re-made twice so the circuit should be good. I have no clue what else to try, please help!!