bigdeewash

When I picked up my C350 in Sindelfingen i was advised to keep my AC on at all times and to just adjust the temperature to where i was comfortable. I was so excited to pick my car up I didn't pay attention to the reason. Can anyone help me with this?

Savage c-300

i havent heard this one before...

joshg1001

i think it is to keep the car from getting that moldy smell that comes from the condensation produced by the AC unit in the vents.

By keeping the aircon on all the time, the water inside will either dry out (in warmer air) or stay in liquid form (in cold AC), which are not ideal conditions for the mold spores to grow.

You dont have to do this. What i do when i turn on the AC is made sure you turn off the AC but keep the air vent on to dry the water inside. Do this maybe 10 minutes before destination

Carsy

+ 1. Why use extra fuel with having the A/C on all the time when it is not needed. Save your pocket, your countrys balance of payments & the planet

BenTrovato

Great tip about the AC. I'll run the fan without AC for 1-2 minutes before destination which should be sufficient.

Glyn M Ruck

There is a good technical reason. You should run your aircon at least weekly if you want decent compressor life even in the middle of winter. Keeps seals in good condition & pliable, circulates the lubricant & releases the refrigerant comingled in the lubricant. This is why Benz recommend it - The oil companies have been trying to get this into all car owners manuals for years. Of course the OEMs would rather sell more replacement compressors.

Agree with warming the system up prior to shutdown to prevent bacterial growth & smells

Diesel Benz

I think the advice was "old school knowledge", the current compressors run continuously and switching AC on or off doesn't have any effect on compressor seals' life.

The compressor works with a variable power from minimum 2% to max 100%.

The mould issue comes from water condensation at the heater core bottom as mentioned. There is nothing that keeps fresh water coming when the car is parked. Keeping the AC on all the time cannot improve things against mould. The advice to dry the heater core just before parking the car is the best approach but unfortunately asks some discipline from the driver, at least myself I would often forget to do that.

joshg1001

I do have an issue with the car that is similar. I dont understand why the recirculation vent is closed even when you dont have air conditioning on. In my other cars, you can open and close it as you wish (without aircon running) to let fresh air in and keep you at the perfect temperature. It is just the car hitting against air, and the air is let in. Wonder why MB doesnt allow for this

Glyn M Ruck

I am well aware the compressors run full time - They need to be made to do some work & cycle the refrigerant. Testing has proven that this extends life. I know where you are coming from though - It's less of an issue than it used to be with a clutched compressor that remained stationary when off.

Uga Uga

Very very true, my next door neighbour never used his aircon, (Jaguar) last week when his wife switched it on the whole thing exploded, gas, fluids etc... The technician said lack of frequent use damaged the seals.

The lady who did my handover at Sindelfingen did say the same, keep it on always, however I don't but make sure I use it at least once a week.

My car developed an electrical fault which damaged the battery, when MB Assistance arrived and removed the aircon filter above the battery, I noticed that when the car is switched of, the vent moves into the open position to allow air to circulate while the car is not in use, this I suppose is desinged to help with the 'foul smell' we talk about.

RLE

True enough. Any compressor without a clutch is a swash plate compressor.
I don't know when they were phased in but even my '01 C320 used one. Which is why you never feel the compressor kick in because the plates change angle slowly. Eliminating the clutch removes one more trouble item.

I run my AC constantly.

RLE

The intake air filter is not above the battery. It's inside, just above the passenger's feet. The plastic box above the battery is a water trap.

peabers

You were referring to this box:

DIY: Heater Blower Intake / Battery

As RLE mentioned the air filter is accessed from the passenger side footwell:

Cabin filter change

Has anyone actually experimented to see what kind of "hit" keeping the A/C running will take on the car? I personally found it to be negligible.

TB5...

awkward... i was told when i take the car off, to always remember to take off the fan/ac. so that when i start the car again they do no start up right away. :\

something about helping longevity of the ac system.

Uga Uga

Correction.....

What I am referring to is the the air intake and not the filter, this can be found upon removal of the water trap.

Uga Uga

Thanks for the illustration Peabers

RLE

Nope.

Uga Uga

Please refer to the illustration Peabers kindly produced, for which I extended my gratitude. The attached picture shows the 'diamond shaped clusters' above the blower. This pivots downwards to shut off the air intake.

Star & Laurel

The Air Recirc / Fresh air valve on the 204 also works based off of speed. It will slowly close of outside / fresh air as the car speeds up. This helps to remove outside wind noise that normally comes through.

As far as running with or without the AC. I typically have it off, but certainly run it periodically to circulate they system and keep seals in good condition. I have not had any issues, but maybe garage parking also helps with keeping any moisture issues down.