Anyone got any thoughts on this one !! what little hair I`ve got is now gone . Local LR dealer can`t sort been to so called Air con specialist (no unusual fault codes from LR diagnostic tester)- in any temp air con fan cuts in soon after start up then runs for about 20 secs then stops for about 20 secs then starts for 20 and so on - from my own research thought it might have something to do with temp sensor in nearside mirror -as member of the household had knocked heavily -but replaced complete unit to no avail. AC operation temp etc seems fine.. Electrician as a day job - Wanna be farmer at weekends !

By aircon fan do you mean the radiator's fan from the engine bay or the cabin fan?

If you refer to the engine bay fans, they should start on low speed soon after you switch ON the AC system and, based on various parameters, they (especially the small one) should increase their speed from time to time and after a while return to low speed.

Thanks for that info -Yes I`m referring to the engine bay AC fan -any idea what /where other sensors are to determine fan speed etc someone said perhaps sunlight sensor might be at fault..but wheres that located? Electrician as a day job - Wanna be farmer at weekends !

Hmm.... The fans are controlled by the engine ECU. The AC compressor also is driven by the engine ECU based on the info from the HVAC system.
There are many factors that contribute to the fans speed, but in short, engine temperature and AC freon pressure are the main ones. The sunlight sensor has nothing to do with the engine's fans speed. The sunlight sensor influence just the cabin's fan speed.

Thanks again for the info Alex. perhaps I`ll get local lot to reset the ECU -load latest firmware or whatever they do and see if that does the trick. Cheers Electrician as a day job - Wanna be farmer at weekends !

Hi,

let them check engine temp sensor to ECM signal - look at live data and graph it.Saw this fault on 2.2 Hdi Citroens few times - if the ECM receives implausible signal it kicks the fans on to protect engine from overheating.
So may be ECT sensor or wiring fault...?

I too had a problem with the condenser fans.
As Alex stated, the fans are controlled by the engine man ecu. The inputs are temp sensors, pressure sensor and low speed CAN signal from the HVAC head unit.
Took mine to the local dealer who discovered the HVAC to engine man ecu CAN signal was at fault. They too couldn't fix it and it took a few calls from them to Gaydon to solve it.
There were no fault codes, but the dealership persevered over two days.

May I suggest you try another dealer as it seems that the one you've used haven't put in enough effort. Another member of the failed FL2 clutch/DMF club, twice.