I've logged this problem with my dealer and hope that they can fix it soon but I thought I'd ask the membership here if anybody has had any similar problem. I've already detailed the issue in an email so I'll just paste the details of main problem here and invite any feedback.
Email begins - - -
The main problem we have is that the fan system slows down to almost stop even though the temperature conditions should require a high fan speed. We have used the car a lot during our recent hot weather when the temperature outside has been around 37 degrees and with the climate control set to only 18 degrees the fan still slows down to a stop for a few seconds and the temperature in the car becomes very uncomfortable until it resumes normal operation. This behaviour occurs when the climate control is set to either manual or automatic, makes no difference, and the temperature inside the car has not reached the 18 degrees set on the system. To be clear, I am not expecting the internal temperature to reach as low as 18 degrees when the outside is 37 degrees, I set this temperature only to test the fan system which I would expect to maintain a constant speed to keep the internal temperature cool, but it doesn't.
My conclusion is that, while I believe the compressor and air cooling system is probably functioning OK, there is definitely a problem with the internal temperature monitoring / fan control system or some other system that influences the fan speed.
Email Ends - - -
Climate control behaves strange
Hi, sounds like something could be wrong but have you tried pressing the Options button on the aircon/heater screen and seeing if the Soft/Normal/Fast settings make any difference? (although this would only affect Auto mode I think)
C3 Aircross Flair 1.2 110 Auto with Parking & Family packs & sunroof
Yes, tried all those and they behave as expected. We have outside temps of around 35C today so I reduced the control value to 17 and the system behaved better, more like a proper climate control. i think there is some hysterisis in the temperature control which might explain why the fan slows to almost stop, then resumes normal to high speed on a repetitive cycle. I'm thinking the cooling cycle makes the interior a little too cold, shuts the fan off, then lets it get a little to warm before kicking in again.
I had a Peuggeot 308 SW and a Citroen C4 before this Aircross and all had similar controls except for the split systems in the 308 and C4. Those two vehicles behaved as I expected them to, and were quite different to the Aircross. We also had an original C3 from 2044 until September 2018 and the aircon in that was phenomenal, cooled down very rapidly.
The Aircross is going back to my dealer on Thursday for investigation.
Update: My car went back to the dealer yesterday, needless to say on the journey of a bout 30 minutes in outside temps of 25 degrees, the system behaved perfectly. They removed all the gas from the aircon system and found there was only 340 grams in it when there should have been 460 grams. It's been re-gassed and seems OK at the moment but time will tell around early August when we get to 40C'ish.