A/C - Blowing smelly air initially at random occassions

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AlterEgo

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XLT 2020, 202a - As the title says, noticed it around a month ago or so.

Sometimes from a cold start the A/C throws smell like kinda stale smelly socks (as my kids describe), at other times it is like smelly toilet cleaner (with acidic smell).

Any idea or clue what may need to be checked plus any link to a service bulletin document would also be nice to have a look myself at the correct spot.

Will a A/C vent cleaner like A/C Pro Vent and Duct cleaner be recommended for an initial remedy, have bought it already. Has anyone used it and can inform of any potential issues I need to be wary before using the duct cleaner spray.

Thanks for your replies.
 

99WhiteC5Coupe

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XLT 2020, 202a - As the title says, noticed it around a month ago or so.

Sometimes from a cold start the A/C throws smell like kinda stale smelly socks (as my kids describe), at other times it is like smelly toilet cleaner (with acidic smell).

Any idea or clue what may need to be checked plus any link to a service bulletin document would also be nice to have a look myself at the correct spot.

Will a A/C vent cleaner like A/C Pro Vent and Duct cleaner be recommended for an initial remedy, have bought it already. Has anyone used it and can inform of any potential issues I need to be wary before using the duct cleaner spray.

Thanks for your replies.



I’d bet the a/c evaporator case is not draining fully or quickly enough, allowing mold and/or mildew to form inside the case.

Under warranty? Have the dealer check the a/c condensate drain.

If not, you can check it yourself. You can clear the drain sometimes with the non-clasp end of a sturdy zip tie.

Dealers and service shops can use a disinfectant foam that is sprayed inside the evaporator core case to clean it, after the drain issue is resolved.

Ford issued a TSB for your year vehicle involving the a/c drain - which MAY be the cause of your issue: https://static.nhtsa.gov/odi/tsbs/2019/MC-10168762-0001.pdf
 

LazSlate

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Had this issue in my BMW. It had adequate drain, it was the design of the coil where condensation stayed on it when the car was shut off.
But important to remember water does not create bacteria alone.

Aside from having possibly the dealer check it out. Make sure your cabin filter is clean and dry. You have to take out the glove box to get to it. If its wet or dirty that could be a cause. You can also blow the heater through the vents on hot to make sure everything is nice and dry. Humid climates can cause even the best ac system to smell.
 

rob4092xx

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Simple fix. Turn your “Recirc” Recirculation off on the A/C so fresh air passes and dries the evaporator out.
 

MariposaRN

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I had what sounds like this issue in my house. My AC guy said a microscopic algae can grow in the coils. When we run heat all the time or cold all the time the coils stay dry and it’s not an issue. In the shoulder season the algae can grow. He said it also happens in cars. We had our coils cleaned and the issue stopped but he said if someone isn’t too bothered by it you can usually just let it blast for a few and then it will pass or will pass when the seasons decided which way to go. He didn’t really try to sell me on a fix.
 

ROBERT BONNER

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I experienced this with my '20 Expedition. I replaced the cabin air filter at 12 months just for yuks. The OEM filter appeared relatively clean; but, I had it out, so I replaced it. At 23 months I started getting the smell (11 months on the replacement filter). So, I replaced the cabin air filter again. The filter that had been in the truck for 11 months looked ugly with a mildewy appearance. Keep in mind that my truck is garaged 10 months/year. I was surprised at the appearance. I ended up replacing it with a "washable" K&N. That fixed the smell problem completely. I'll revisit this post when I check it in a few months to report on how the washable filter does.

Note that I had a 2011 Fusion that my mother-in-law drove that was dealer serviced for several years and parked outside. The dealer never serviced the Cabin Air Filter. When it was 6 years old I started servicing it and immediately noticed the smell that my MIL had gone nose blind to. The Cabin air filter was completely plugged and had probably been in bypass mode for years. Changing the filter was not enough. The evaporator was full of mildew. I used a commercial evaporator foaming cleaner and it did a great job of cleaning it and eliminating the odor.
 
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AlterEgo

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Update:
=====

Got the Cabin Air Filter replaced and A/C duct system cleaned/refreshed on my last recent periodic service visit. The problem is solved now - even the dealership serviceman said its a known issue which happens to moisture accumulation and mold/fungus inside the ducting/filters.

Yeah it was a paid service and not covered in my FlexiPro service prepaid coupouns I have bought for regular maintenance.
 
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