In answer to a higher post yes a manual switch could be fitted but would mean that the cooling fans are running at high speed thus overcooling the coolant. There must be a relay or resistor somewhere that reduces fan speed when the aircon is switched on, as mentioned above the fan will cut in or out dependant on air flow through the aircon radiator ie vehicle moving or stationary.mikeonb4c wrote:Indeed! I haven't thought that one through fully yet. You can test they come on with aircon by - with key in start position but engine not running - pressing in the aircon button (manual aircon - not sure how you do it with climate control). You should hear the rad. fans start running.Alison01326 wrote:Really stupid question about checking radiator fans, but does that mean I have to pull over and run round the front and have a listen?
You have to find a position from which you can observe rad fans running when engine is running and aircon is switched on. I'm still waiting for someone to tell me from my query higher up, whether it is normal for the compressor (condensor?) to cut in and out when working properly. I'd assumed it was as the compressors job was to compress something up to a certain pressure before switching off, and switching on again when a sensor detected pressure had dropped and needed rebuilding. But this talk of condensors switching on and off because rad fans aren't switching on properly has got me confused.
It is quite normal for the condensor to cut in and out as you say when pressure is reached but it also has a thermal cutout for protection if the aircon fans are not working. One thing I have done to test how cold the aircon can get (because the fans don't start up to cool normally) is with the vehicle stationary and the bonnet raised have a hosepipe spraying onto the aircon radiator obviously with the aircon switched on, leave for 5 mins then open the bongo and feel how icy cold it is inside. Incidently this was the only way I could get the system re-gassed without the fans working properly. But does anyone have any idea what controls the fans for the aircon, is it a fault in the climate main control unit or a relay somewhere or a resistor????