Aircon only working on passenger side

[ahoythere]

Hello - my post relates to a 2007 E-class estate 220i (W211).

A few weeks ago, the red light on the aircon button started blinking and the aircon would not come on. Never happened before. Took my car to a garage (not my normal Mercedes indy) who tested for leaks and re-gassed the system. Aircon worked pretty feebly, then stopped working on the driver's side. Cool air only on passenger side, but it is barely noticeable.

Could it be a problem with the actuator which controls the flaps or the duo valve or a lack of refrigerant?.

This Youtube video shows how to do a test for refrigerant level, but it's for a left-hand side drive W211 and I'm hesitant to do the test in case the up and down arrow instructions are different for right-hand drive models.

Advice appreciated on possible problem, big job/small job to fix, and suggested next steps.

Thank you.

 

[00slk]

I had a similar issue with my s211 and it turned out to be the duo valve under the brake booster. I left it to my Indy to sort out.

 

[ahoythere]

I had a similar issue with my s211 and it turned out to be the duo valve under the brake booster. I left it to my Indy to sort out.

Thanks for the swift reply - will take it to my Indy. Out of interest, does replacing the duo valve involve removing the dashboard or can it be accessed from the footwell?

 

[00slk]

The duo valve can be accessed from the engine bay, it is mounted under the brake master cylinder. It is a bit of a faff to get to it and undo the hoses, that's why I left it to my Indy. The Duo Valves are about £40 to buy new from Mercedes.

 

[ahoythere]

The duo valve can be accessed from the engine bay, it is mounted under the brake master cylinder. It is a bit of a faff to get to it and undo the hoses, that's why I left it to my Indy. The Duo Valves are about £40 to buy new from Mercedes.

That's super helpful - many thanks.

 

[M80]

I would want to eliminate AC low pressure 1st.
The AC machines test under vacuum, that doesn't emulate it running.
A nitrogen test at above 10bar pressure is a far better integrity test of the AC system.

Now it's been regassed a pressure test should show if your system has held the gas. The issue there is that running the engine can create pressure with little gas.

 

[star]

I would start at low ac gas, get it re gassed. That’s where we start, from experience

 

[ahoythere]

I would want to eliminate AC low pressure 1st.
The AC machines test under vacuum, that doesn't emulate it running.
A nitrogen test at above 10bar pressure is a far better integrity test of the AC system.

Now it's been regassed a pressure test should show if your system has held the gas. The issue there is that running the engine can create pressure with little gas.

Thanks Martin. I am also wondering whether there is a a leak or whether the system was re-gassed properly. Will mention this to my Indy.