Cooling Fans

[Alan_M]

Can someone help me here;

It seems my fans are starting to have a mind of their own these days. Only recently, the fans kick into high speed for some unknown reason, which I believe is linked to the A/C.

Low speed fans should only kick in when the engine temperature reaches 97°C & it will turn off when the temperature has dropped to 90°C and when the air conditioning system is switched on. It will run permanently regardless of engine temperature. Car sits at just under 80, never gets hot.

High speed fans should only kick in when the engine temperature reaches 107°C, when the A/C refrigerant high pressure threshold is reached and when the temperature sensor circuit goes faulty. (open circuit)

What exactly does high pressure threshold mean on the A/C? Is this a fault or just a consequence of running the A/C for a duration?

[mattgreene]

High Pressure Threshold means, the gas in the high pressure side of the air con system has got too hot, when driving the condenser provides plenty of cooling, when stationary on a hot day, theres no air flow and its reaches a preset temp and turns them on to high to cool the gas down.

[Alan_M]

Dragging this thread back up, I ran a diagnostic and actuator testvia Planet on my HDi today (why not as I was investigating/clearing some fault codes). Tested the cooling fans, and I understand the Planet test is an actual run of the fans not just a relay test.

Well, I could hear the relays clicking behind the grill, but no fan running on low nor the high speed test.

Firstly, can someone confirm for me the fan test on Planet is the actual running of the fans, not just the relays....

Secondly, would the failure of the fans cause my A/C not to work?

It worked fine late Autumn last year, freezing cold if you wanted it. Now, it 'attempts' to cool the air, as the air is cooler than a non A/C air would put out. But, the compressor does not kick in (no rev drop/pick-up when switching ON A/C).

Obviously, I need to sort the cooling fan before anyone mentions this as a priority!