Air Con only blows hot, unless set to low.

[Aubergin3]

Hey guys/gals,

So i just bought an w220 S Class 320 CDI and its fantastic, all the toys and engine i mean, however didnt realise until a few days after purchasing that the Air Con system is a bit of a weird one.

Set the temp to 22 degrees as i would in my other cars, but for some reason it just keeps blowing hot air, even past the 22 degrees temperature i know and am comfortable with. Down to 12 degrees and its still blowing ridiculous amounts of heat at me.

However flick both passenger and drivers temps to LOW and cold air starts blowing out, flick a temp above on either side and its back to scorching heat...

Have checked the air con diagnostics (holding rest and flicking through the codes), the sun sensor and malfunction codes, all seems to be fine.

My next step is to get the system re gassed up and see if that helps as it did somebody else on here.

Any other suggestion would be much appreciated.

 

[Spin_bowler]

Have you been doing this today (or recently) or has this been the case over a period of time? How long are you letting the system run before changing the settings?

 

[Alps]

It's a common problem, duo valve needs replacing they also call it heat exchange motor

 

[Aubergin3]

Have you been doing this today (or recently) or has this been the case over a period of time? How long are you letting the system run before changing the settings?

Well i have only had the car a few days, been on the motorway for a good few hours and still seems the be wrong.

Duo valve seems like it could be the culprit, will do a quick search to see DIYs, advice on where to purchase said duo valve.

But before i buy this you guys recommend the A/C re gas attempt? Guess it would do no harm.