Constant Air Con Change

[Topboy]

Morning Guys.

I have just this morning booked my 04 C Class in for another air con treatment change. Since owning the car (30 months), this will be its fifth change.

When I get in, the smell from the air con is foul. It's a really nasty stale socks/pants sort of smell! Although this passes within about 20 seconds it really is unpleasant.

When I have the air con treated it's lovely but it just doesn't seem to last although the air con works fine.

Having previosly owned Volvos, Renaults (boohiss!) etc, I can only remember having this treatment done once on all my previous cars.

Anyone else get this lovely bacterial problem?

Please note that I have personally checked my own socks and pants and the wife agrees that they don't smell too bad!

 

[tobro]

I am sure there are other threads with this info Topboy but the smell originates from the evaporator (heat exchanger located behind the dashboard) and is caused by a build up of mould/bacteria. The bacteria grows due to moist conditions inside the evaporator box. It is a common problem and is treated with the use of anti-bacterial spray which can be introduced directly into the system via the dashboard vents using an extended nozzle. Alternatively the anti-bacterial agent in gaseous form is introduced to the interior of the vehicle and the aircon sytem run on recirc for a period of time. Both treatment methods will obviously only be effective if carried out correctly.
I have worked with vehicle aircon systems for a number of years and would be questioning the methods of a technician who has had to revisit the same vehicle so frequently.
Needless to say damp conditions in the evaporator box should not prevail and frequent use of the aircon sytem (even in winter) will help prevent any problems. The box is also fitted with a drain which will normally leave a puddle under a sationary vehicle which has the aircon running. Is your drain blocked?

Good luck

 

[Topboy]

Tobro,

Thanks for the advice.

I have the aircon running all year round.

I'll check the drain and investigate further.

Cheers.

 

[Andy Wr]

When evaporators get really bad, it is necessary to strip them to gain direct access or even remove them for cleaning or replacement.

 

[oigle]

Tobro,

Thanks for the advice.

I have the aircon running all year round.

I'll check the drain and investigate further.

Cheers.

Would suggest that you have identified your problem here. This has been posted before, but to repeat, it is important to dry out your aircon system regularly to prevent the growth of bacteria that causes the smells. The easiest and best way is to run fresh air through the system regularly WITHOUT the aircon operating. Turn off the aircon 5 - 10 minutes before the end of a trip and let fan assisted fresh air circulate through the system which will dry out the water produced by the cooling effect of the airconditioner. Running the car without aircon on nice cool days is ideal to dry out the system and kill any bacteria - they need moisture to breed.

 

[Topboy]

It just seems strange that I have never encountered similar problems with, shall we say, lesser cars!

 

[bazzle]

I have a similar problem. It turned out to be the Dust / pollen filter.

Bazzle

 

[Phil D]

Hi - I've experienced exactly the same thing - (54 C Class) - recently regassed & deponged at Kwik Fit - much cooler now but nasty smell is back after only a month - can anyone advise where the drain is that could be the problem - also as per previous post - this is my fourth or fifth car with aircon - including a W202 - never had this issue with any of them
Phil

 

[Glenn Smith]

I have a similar problem. It turned out to be the Dust / pollen filter.

Bazzle

This is where i would be looking, also check whether water is entering through the blower inlet, i've not encountered this on my Mercedes but have on other cars, has the car been or is it smoked in?

 

[tobro]

- can anyone advise where the drain is that could be the problem -

The evaporator box is located behind the dash and the drain (smallish bore rubber/plastic hose) will normally be routed to the front side of the engine bulkhead and terminating level with the underside of the car.

 

[oigle]

It just seems strange that I have never encountered similar problems with, shall we say, lesser cars!

I wonder if your "lesser" cars have had dust and pollen filters. They can amplify these problems when they get damp. New one fixes it for a while until bacteria builds up on the new one. Keeping the system dry really does rectify the problem.

 

[Wezzel]

I had a problem last year.

I bought an aerosol from Hellfrauds which kills the bacteria. Basically you leave the car ticking over for 10 minutes with the aircon on and blower running full pelt with the centre vents open. The aerosol is placed on the floor of the car and triggered (when you press the aerosol it squirts upwards and keeps going until it's empty).

I also replaced the pollen filter and the smell was gone.