W169 Air Conditioning Problems


I purchased my W169 in December of 2012 and up and until this month (early May 2016 )have had no problems or concerns, yes I have serviced the car and had new tyre's fitted but that's it. Very pleased all round.

Anybody living in the UK will be aware that the latter part of 2015 and early part 2016 certainly have not required air conditioning to be turned on to cool the vehicle, as the weather has been appalling and use of the heater was more appropriate.
So in May of 2016 when I first tried using my Air conditioning system was surprised to find that air was not cooled which indicated to me that either the system needed re-gassing or I had a leak and that the refrigerant gas had escaped

Just one journey without it on a hot day convinced me that it needed investigation and soon.

Those of you who have read the W168 pages will be aware that I had to get the air conditioning sorted out on that car as I felt is was not performing as it should, for details, see page 31. W168 section. I had that task completed by National AirCon who did a good job, by just draining and re-gassing the system no further problems were experienced for the rest of my ownership over many years.

However when I contacted them about the W169 they indicated that this model has a problem with the condenser and that may well be the cause of the Air conditioning failure in this instance.



I arranged for them to come and test the car and to determine what the problem was, as this is not a job you can do yourself unless you are in that trade.
True to their word the condenser had two leaks although there was still a small amount of gas in the system.

It is worth mentioning at this point that Mercedes Benz advise against switching the Air conditioning on if the system has become de-gassed (void of refrigerant gas) as this can damage the air conditioning compressor.

The leak was detected using a gas detector which beeped when the probe was held in the area of the leak so there was no doubt in my mind that was the correct diagnoses, this mechanical failure will not show on EOBD or OBD diagnostic tools so do not be talked into paying for one.

Special Note
At this point I should mention that if like mine your car is fitted with parking sensors and auto parking (parktronic) then you will need to disconnect the battery before removing the front spoiler into which the sensors are situated. If you fail to do this the front sensors will not work when you next use the car.
A quick check that these are working after the replacement of the condenser or any repair where the front spoiler is completely removed with the sensor multi-pin connector disconnected can be carried out by driving up to any obstruction in front of the car.
If the sensors do not work after the job is complete,disconnect the battery for 15-20 minutes then re-connect the battery firstly turning the light switch to at least side lights, this will allow the ECRU to re-set and will delete the problem.
Fault will not show on Diagnostics equipment so do not waste your money paying for a test.

Irrespective of where you get your condenser replaced tell them if you have parking sensors and auto parktronic and that the battery needs to be disconnected. On the 6th May National Aircon returned to my property and fitted (Note the change in colour)the new condenser which is located in front of the radiator directly behind the front grill, an after market part was fitted rather than one supplied by Mercedes Benz parts which kept the cost down.

The operator,Simon said he had replaced many of these units and it was very obvious to me that was the case he clearly being aware of all the fixings and how to best release the condenser.
The whole job took Simon and his mate Claire 1.5 hours an that was with a cup of tea.





The whole of the front of the car has to be removed and various parts slackened off just to get the condenser out. But firstly along with the complete system drained of any residual gas.

This gave me a change to clear the dead leaves and road dirt that had accumulated being the spoiler, impossible to get at when in place.







Although it is difficult to see in a photograph where the refrigerant gas has leaked the grill of the condenser has gone black, on my old condenser there were two area's where the unit had leaked.
























The new condenser was then fitted and a vacuum pump attached to the system when this was complete the system was re-charged with the refrigerant gas which also includes a quantity of oil which lubricates the compressor which is an integral part of the system and a dye which helps to locate any leaks in the future.



From what I saw there were only two slight problems, one was removing the centre pins from the plastic securing clips and the second in disconnecting the multi-pin connector which provides power to the parktronic and parking sensors. In the case of the clips the problem was solved by my providing a tool I had made up for removing the pins which I passed onto Simon for his future use.

The tool is simple but effective and does not take much time to make, I simply made another tool.
In this case, One end removes the centre pin and the other the main body of the clip from the body work which saves time and salvages the clip. The crank at each end provides the leverage to remove the respective parts.

















To release the multi-pin connector firstly withdraw the grey clip.
Then press down on the plastic clip in the multi-pin block at the same time easing the two sections of the block apart.
Remember to replace the grey clip as this is a safe guard against the multi-pin block coming apart.
The last thing you want when reversing or driving forward is for the parking sensors to fail due to the block having separated.
In this case Mercedes-Benz have fitted belt and braces to prevent that occurring

If the battery has been disconnected reconnect, remember to turn you light switch to at least side lights before doing so

The sensor system can be tested by simply driving towards any obstruction ensuring that the sensor lights display centre dash. If the job has been undertaken without firstly disconnecting the battery and the front sensors do not work, disconnect the battery for 15 to 20 minutes and then reconnect, the system will re-set.
Re-test to ensure the system is working correctly.


The complete job which included two visits and provision of the condenser, gas, dye, etc was 400.00. I consider this good value when the comfort that air conditioning provides on a hot humid day is taken into account. Certainly I missed mine and it was only out of order for a few days when needed.


The Air conditioning is now working better than it has ever done.
I had it checked when I first took ownership of the vehicle because I did not feel it was as efficient as the system on the W168. but I was told it was OK

Needless to say I should have used National AirCon to check it rather than a local garage.

Simon and Claire are based in the South East of the UK, there contact number is 01273.202075 for AirCon South east call:- 01342 323344















After being repaired the temperatures achieved, reached in two minutes from start 84 degrees F down to 42F (26C down to 6C) more than cold enough even on a hot day.

It is interesting to note that the handbook for the car does not make it clear whether the light should show on the Air con switch for system to be On or Off?

I can confirm that the light SHOULD be ON for the system to be working with the fan control set to at least one(1) on the fan dial
You will appreciate that when the system fails neither position produces cool/cold air making it difficult to acertain whether the Air con is On or OFF making it difficult to ensure the compressor is not used.

Although the removal of parts could be undertaken DIY it is not practical because you still have to get professionals into check for leaks using specialist equipment and re-charge the system the parts having been replaced. My car was not off the road at all, I was able to use it while the part was ordered and then simply make it available at my home for the parts to be fitted. I would strongly recommend National Air Con to undertake this task. Thank you National AirCon, Simon & Claire




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