w218 cls500 cooling fan on full and no a/c

[Gbrowncls55]

Hi all,
Yesterday i noticed the a/c was not working (although this morning it was!) so I took it for a regas and it is now full with no leaks detected. but the a/c does not work at all and in fact blows warmer air than with it off and the engine cooling fan runs at full speed all the time. Feels like a temp sensor but all suggestions welcome . Its an M278 4.7 bi-turbo. apart from those two things it runs as normal as far as i can see. I have an Icarsoft MB2 and there are no a/c fault codes showing. engine temp guage is in the usual position.
Any help apreciated.

 

[Gbrowncls55]

More info. Once the car has been standing for an hour or so and so cooled down a little the aircon works and the engine fan is not on full. Aircon then seems to work whilst running right up to normal coolant temp. But after you stop and leave the car in the sun ( hot day) for a bit when I start car fan comes on full and Aircon doesn't work. Is there a temp sensor that can turn Aircon off at a certain value or if it goes bad? Thanks

 

[Kerabo]

I am not sure if this applies to Mercedes but haveworked on cars that when it’s doing a DPF regen needs to load the engine to keep it hot. To do this it turns in several things like rear window demister And cooling fans to load the alternator and keep it hot until the Re-Gen ends.

 

[Gbrowncls55]

Its petrol so I doubt that will apply but it feels like something is switching the fan on and a/c off deliberately as you say. Yesterday drove about 40miles a/c worked first two miles then stopped then 5 miles from destination started working again for no aparent reason. No icarsoft fault codes. think its time to get it on STAR

 

[Gbrowncls55]

In case anyone is interested / has the same problem it turned out to be a faulty aircon pressure switch that was switching itself off when it got hot. All well now.

 

[Jigglyjohnson]

I'd go with the a/c pressure switch
Common issue the switch will relay a higher pressure reading to the ecu which I'd wrong so the ecu with put the fan on the cool the condenser and thus bring the pressure down but as the sensor is faulty it doesn't see the pressure drop so keeps the fan running