W211 air con light flashing then off

[jp]

Haven't been on here for a very long time due to my '07 W211 being 100% reliable
First problem for ages:
Turn air con on, light comes on, flashes and then goes off.
Before I take it to be plugged in and diagnosed thought I'd check on here that it's not something silly like needs a regas.
Any views/ help most appreciated.
Thanks

 

[onefortheroad]

Itll be low on gas , it will also need to re enabled by the ecu following a regas, using icarsoft scanner or simililar.

 

[Alps]

as above, get the gas topped up, I think they need resetting after also using STAR or other diag tool.

 

[Botus]

when they reach this age the low gas tends to come from the condenser finally saying 13 winters of salt have rotted me past my sell by date

I had to put one on the S class at only 55k miles from new, one in stock at MK £850 !!! bought the same OEM part through some parts factor for £125.... then u have to fit and gas it.... and you SHOULD do the drier which is another £200...

go out on a sunny day open the bonnet and look round the two sides of what should be a clean aluminium rad lookalike... if you have dark dusty patches then its had it

 

[mioba]

Usually the compressor switches off because there is no gas. Thats why it switches off. If you have gone 14 years withoout a ragas thats pretty good. My w220 has one fill since 2004.

 

[MJJ]

As above, the flashing LED is the HVAC module telling you there is an error in the system - most likely low refrigerant pressure due to low levels of refrigerant. It is likely you will have a leak given the age of the car, and an aircon specialist will be able to trace a leak fairly easily.

Also as said above, a fixed system will not start working again until the error code is reset so if you are considering DIY'ing this, now would be the time to buy a Carsoft diag tool or similar - you can read the error, and ultimately reset the error once fixed.

You could simply get the system re-gassed, and the re-gassing machine will test for leaks before re-filling - very small leaks won't be spotted by the machine though, and you may be back to square one in a few months.

On my 180k mile '09 S211, which had a leak, it was the rubber o-rings on the combined inlet/outlet to the condensor, £10 for the parts and an hour's easy work. On mine, the air con compressor failed shortly afterwards, I assume as it had been operating with low gas. The 211s are fitted with a variable displacement compressor, so always on - new Denso one was £270 (plus £50 for the required drier) from Autodoc and another hour's easy fitting.

Martin.

 

[alexanderfoti]

all of this +1

 

[jp]

Thank you all for your responses, taking it in next week and fingers crossed it just need a regas.
It was regassed about 5 years ago, apparently the machine had an issue but the very nice man said it should be "fine"

 

[M80]

Take it to ATS and ask them to pressure test it. I think they use nitrogen.
It's a more reliable test then the machine purge, and faster. Often you can hear the gas escaping if it's the condensor.