W205 AC faulty

[James15678]

Hi all,
I have a w205 with this issue:
Ac on drivers side will blow cold if fan speed is set to less than speed 4, at about 8⁰, once fan speed goes higher so does the temperature at the vents, up to about 20⁰. The passenger side is roughly always 10⁰ hotter.
I have no fault codes and all live data is within parameters.
Ac clutch is engaging and doesn't stop when fan speed is increased, radiator fan is not constantly running unless ac is on.
Live data shows ac pressure sensor at 5 bar before engine is started and raises to approx 9 bar when ac is on. I took it to a garage to have air con pressure checked and they said it was all OK.
Any help would be appreciated

 

[IvorH]

Did you mean to type 8 degrees? I run mine at 18 degrees on fan speed 3 without issue and should I need to increase fan speed, it will do it, but I really don’t need it, even at the height of summer.

 

[James15678]

Yes, 8⁰ at drivers side vent, when temp is set to low. But as fan speed increases the temp goes up.
Thats the issue soon as fan speed increases the temperature at vent goes up.
So last week when it was 30⁰ + outside, I had it set to 18 on display, ac on and auto, but in auto it was putting fan on full speed to cool the interior, but it was blowing out air at 20 odd degrees.

 

[IvorH]

That is odd. I’ll give it a try with the same settings tomorrow and report back!

 

[Jobsworth]

That does sound odd. If the system hasn’t been serviced for a while I would try that first. There may be moisture in the system. The vacuum stage of the servicing process removes the moisture from the system

 

[alabbasi]

Check the pressures, on some cars, you can do that from the climate control system. I suspect that it's low. You should expect vent temps to go up as the fans blow more air. That's how heat transfer works but if it's not efficient, it's probably low on gas.

 

[IvorH]

Well, as promised, I checked mine out and it went from 18 to 17, to 16 then to Lo, so Zi hano idea what the temperature was, sorry James!

 

[James15678]

That does sound odd. If the system hasn’t been serviced for a while I would try that first. There may be moisture in the system. The vacuum stage of the servicing process removes the moisture

Check the pressures, on some cars, you can do that from the climate control system. I suspect that it's low. You should expect vent temps to go up as the fans blow more air. That's how heat transfer works but if it's not efficient, it's probably low on gas.

Was recharged about 2 years ago, and had pressure checked last week, admittedly it was at kwik fit and they said pressure is ok, xentry is showing 5bar pressure when engine is off

 

[alabbasi]

You should measure with the engine running and a/c on but even that said, 5 bar seems way too low for static pressure

 

[James15678]

That is 9bar and raises to 11ish when it's been on for a while