Ibyellow

My s320 cdi 2006 has an AC problem. It seems a bit of a strange one to me.

When the AC is turned on, so should be cold I get cool not freezing air blown from the vents.

When the AC is turned off I get colder not freezing air blown through the vents than if it was turn on.

I can hear the hiss when activating the AC but not sure if it should be as loud in the car as it is.

So what/how should be checked first?

Regas?
Solenoid?
compressor?
Something else?

Duo valve is arriving tomorrow but I don't think that's the issue. I won't change anything until I change that anyway.

Ultrakla$$ic

Do you have a set of AC gauges to check for amount of charge in system?? Can you see the compressor engage when the AC is turned on (this would require you outside the car while someone is inside the car activating the switch)....this is where I'd start.

If the air is colder when turned off coming through the vents than turned on you must live at the North Pole this time of year because it's hotter than the surface of the sun in most of the globe.

BOTUS

your first post isn't that clear.... how are you turning it off?

on real cars the light is to say oi you idiot you turned me off
whereas small cars have a light to say oh someone turned on the AC

if its colder in the other condition, that seems like your off is really on ? on german cars the bit at the front the condenser is made of chocolate and the gas escapes - I had a new one at 10 years old and 55k miles

buy a porsche and you'll be lucky to get 3 years

the days of the massive clunk from an electromagnetic clutch is well passed on most cars after 2005 - they now have a swash plate giving a variable rate AC compressor and these are much more tolerant of low gas situations and keep going but doing little - the earlier stuff would just trip to always off with a low gas cut out

if you hear a noise like the TConverter is messing about and its a bit like gear whine and changes with revs its more likely the AC gas is substantially low
mine seems pathetic compared to other cars even though its the large systems with rear AC and has 1200g of gas (even after the new condenser was fitted and regassed by "professionals")


,

Arrie

Most people think the refrigerant must be low whe a/c quits cooling but it does the ssme when overfilled. Difference is that overfilled gives a little cool when empty does not give any.

Let some out sand see if improves. If not then recharge.

Get meters for it. They do not cost much.

Senecat

pull codes

cruiser02

Friend just went through this, it was a bad compressor.

JohnLane

OP and Botus... You both have a compressor that has given up. More often than not giving it a new expansion valve at the same time will do good things for just how cool it gets.

Ibyellow

Everything is sorted at least for now.

Basically it was low gas. As the dealer had only topped it up it had just enough into not turn its self off.

An AC specialist checked everything and has said due to age and it being standing for 6 months the seals have probably degraded. No leaks detected. He thinks as it wasn't filled up to the correct amount and my turning it off most of the time that the oils not being circulating enough to help. No fault codes. He thinks it may be a case of refilling it every year. Or topping up.

Now my duo valve is fixed. I now have freezing cold air all round. Will see how long it lasts. I hope I don't need all the seals replacing.

BOTUS

never turn off AC or is just goes wrong - domestic fridges are usually left on and last 30 years

BenzV12

Good for you , I know how terrible it is when your A/C doesn't work properly .