Author Topic: Persistent pong from the ventilation system  (Read 8775 times)

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Offline JerryB

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Persistent pong from the ventilation system
« on: June 30, 2015, 06:38:14 pm »
I have previously treated my car with Air Con bomb which has done a bang up job of getting rid of the musty 'rotting carpet' smell caused by bacterial accumulation in the system.  Unfortunately, when I treated the system this time the rotting carpet smell was replaced by an overpowering smell I can only describe as well stewed sweaty feet.  In an attempt to fix the problem I replaced the pollen filter (which was black and full of fluff, leaves, seed pods and I don't know what else).  This did not cure the problem so I treated the system again with Comma air con cleaner.  The smell still persists although the citrus tang of the Comma does alleviate it a bit. The problem is worse in the hotter weather when you really need the air con.  I suspect that the ducts contain dead vegetation or worse.  Can anyone tell me how I can access the ducts or does anyone know of a cure? 

Offline JerryB

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Re: Persistent pong from the ventilation system
« Reply #1 on: July 25, 2015, 02:02:56 pm »
Just a little update after much trawling of the internet.  One of the US sites specified a product which you have to cure by running the heater at full blast for 10 mins.  I didn't try to get the product but did wonder if the heat might kill whatever's lurking in the ducts so I ran the heat on full on one of the hottest days of the year.  The smell has diminished considerably.  I plan to have another go and then air con bomb it again and see if I can kill it completely.  I've also been advised to run the fan for a few moments after switching the air con off to reduce the moisture in the ducts which I am trying to remember to do.  I don't normally answer my own questions but I thought this may be of help to anyone with a similar problem.

Offline Westbury71

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Re: Persistent pong from the ventilation system
« Reply #2 on: July 25, 2015, 03:00:57 pm »
Just a little update after much trawling of the internet.  One of the US sites specified a product which you have to cure by running the heater at full blast for 10 mins.  I didn't try to get the product but did wonder if the heat might kill whatever's lurking in the ducts so I ran the heat on full on one of the hottest days of the year.  The smell has diminished considerably.  I plan to have another go and then air con bomb it again and see if I can kill it completely.  I've also been advised to run the fan for a few moments after switching the air con off to reduce the moisture in the ducts which I am trying to remember to do.  I don't normally answer my own questions but I thought this may be of help to anyone with a similar problem.

 ;D Nothing wrong with answering your own questions, at least you get a reply :-)

Good idea running the hot air. Not heard of that before, but makes total sense when you think about it. Heat kills bacteria, which is clearly lurking in the vents somewhere.

With regard to running the fan after using the air con, this is a must. Also remember to make sure the system is not on recirculation mode, to ensure that it is fresh air that's drawn through the vents.

Offline BBOY

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Re: Persistent pong from the ventilation system
« Reply #3 on: July 26, 2015, 06:43:07 am »
Just a little update after much trawling of the internet.  One of the US sites specified a product which you have to cure by running the heater at full blast for 10 mins.  I didn't try to get the product but did wonder if the heat might kill whatever's lurking in the ducts so I ran the heat on full on one of the hottest days of the year.  The smell has diminished considerably.  I plan to have another go and then air con bomb it again and see if I can kill it completely.  I've also been advised to run the fan for a few moments after switching the air con off to reduce the moisture in the ducts which I am trying to remember to do.  I don't normally answer my own questions but I thought this may be of help to anyone with a similar problem.

I always pump heat through the system after using the a/c, even as you mentioned on a hot day to help dry the the system of any condensation inside it (or is it dew?).

Also I run the a/c once a week even in the winter as the refrigerant also acts as a lubricant in the system to stop the seals from drying out. It's worth noting this as not many people are aware of this.

I am pleased that you've managed to inexpensively solve your problem.

Offline mareng73

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Re: Persistent pong from the ventilation system
« Reply #4 on: June 05, 2019, 09:34:30 am »
I have previously treated my car with Air Con bomb which has done a bang up job of getting rid of the musty 'rotting carpet' smell caused by bacterial accumulation in the system.  Unfortunately, when I treated the system this time the rotting carpet smell was replaced by an overpowering smell I can only describe as well stewed sweaty feet.  In an attempt to fix the problem I replaced the pollen filter (which was black and full of fluff, leaves, seed pods and I don't know what else).  This did not cure the problem so I treated the system again with Comma air con cleaner.  The smell still persists although the citrus tang of the Comma does alleviate it a bit. The problem is worse in the hotter weather when you really need the air con.  I suspect that the ducts contain dead vegetation or worse.  Can anyone tell me how I can access the ducts or does anyone know of a cure?


Prevent leaves and seeds from entering  by not parking under trees and garaging at night.

Another thing that causes smells is the windscreen washer fluid thats not been used  for some time and gets hot. This needs to be suctioned out refilled with clean water with a drop of washing up liquid and pine disinfectant added first then flushed through the washers then add clear water to rinse.  I did mine the other day and it cleared it straight away.
The smell which is quite strong only happens when the washers are used. Also try to used softened water from a Brita jug for your washer bottle then add the concentrated fluid, rather than buy coloured water from Halfrauds, garage forecourts and supermarkets that freezes.
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