E Class W211 Estate 2006 air conditioning problem

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e220estate

Active Member
Joined
Sep 16, 2015
Messages
106
Location
Wiltshire
Car
E220 Estate 2006 S211 T model
AC performing well until 2 days ago. Now, first start of the day - ice cold air and both the dash red dial/switch LED's on. Drive for 10 mins and air coming out of all ducts becomes ambient - every 10-ish mins I get a blast of cold air and then back to sweat city! Red LED's stay on all the time- no flashing (as in 'too little AC pressure'). Leave for 15-ish mins after stopping and the same thing happens when I start up.

Prior to this problem, have recently topped-up the AC refrigerant (didn't have this problem prior to the top-up) so is it possible I have put too much extra refrigerant in the system and am creating too much pressure? Is there an excessive pressure sensor in the system? Does anybody know what the AC internal pressure should be? Any other thoughts? TIA
 
I think if you had too much pressure in the system, your cooling fan would be blowing crazy loud like you’ve never heard before.
There will be an issue somewhere, best get an indie or an AC specialist to diagnose it, I’ve just repaired a similar fault with a w212 which turned out to be an intermittent short circuit with the AC compressor, rare fault but expensive to rectify.
 
AC performing well until 2 days ago. Now, first start of the day - ice cold air and both the dash red dial/switch LED's on. Drive for 10 mins and air coming out of all ducts becomes ambient - every 10-ish mins I get a blast of cold air and then back to sweat city! Red LED's stay on all the time- no flashing (as in 'too little AC pressure'). Leave for 15-ish mins after stopping and the same thing happens when I start up.

Prior to this problem, have recently topped-up the AC refrigerant (didn't have this problem prior to the top-up) so is it possible I have put too much extra refrigerant in the system and am creating too much pressure? Is there an excessive pressure sensor in the system? Does anybody know what the AC internal pressure should be? Any other thoughts? TIA[/QUOT

As this happened after (what seems to be?) a DIY re-gassing it seems likely that this is the route cause.This is one of the many reasons that these kits are not recommended. They do not vacuum out and measure remaining refrigerant, do not recover, measure and add the correct quantity of oil etc.

I would go to an A/C specialist to get the system properly checked, possibly drained and re-filled.
 
Could be external air temp sensor.had exactly the same on my SL. Get it on star
 
Where are you based?
 
Thanks all for the thoughts - especially in connection with DIY top-up - which is what I did. I used the gauge to check the pressure as per the instructions and the reading was to the lower end of the green segment (or just OK). Sort of what I would expect after the last professional complete re-gas 2 years ago when a stone punctured the condenser.

I decided to add some R134a refrigerant and raised the pressure to mid green range. I did this on 15th. July and all continued normally with AC function until last Thursday 2/8, PM (AM it was fine) when the symptoms started. So as to cause, my reasoning went that the only external change was the extra R134a I put in or that there had been a spontaneous component failure which I could do nothing about anyway - unless I had missed something (eg an AC reset which I often did on my Ford Scorpio), but I can't find any details after a search (well, there is one but my switch layout is different to the example). I had sort of got to the point where I expected that I would need to visit my local indie for a resolution (I am located in North Wiltshire, just south of Swindon) and I wanted to validate my conclusions first.
 

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