A/C smell when switched off

[Bardo]

Hi everyone

After searching for a recent thread on how this can be resolved I thought I'd see if anyone else had a similar experience/fix.

On my 2014 Lexus IS300H, I've noticed that if if the A/C is on regardless of the air circulation setting it does not smell. However, as soon I switch the A/C off the smell that is emitted via the vents is vile. The A/C blows ice cold, but in the winter I do notice that the windows 'steam up' more often than in my previous car. Especially on the rear screen.

So far I've tried spraying the pollen filter area with Dettol Antibacterial along with each of the vents, followed by running the a/c on an off on a high heat setting for about 30 minutes. The pollen filter was changed recently and when I took that out there was no smell. I've also checked the small black rubber hose in the passenger side foot well, removed it and some water came out but quickly dried up in the recent heat.

I've read that spraying a specialist air con cleaner such as this (https://www.lexuspartsdirect.co.uk/parts/lexus-ux/lexus-ux-2018-present/lexus-ux-cooling-heating/lexus-air-conditioning-system-cleaner/) via the drain pipe could help, but not sure how big of a job it is to access the pipe from underneath.

Any advice or fixes will be appreciated. Thank you.

 

[cruisermark]

HI Hiten

I always leave the AC running all year round and have never experienced any problems or smells (mine is 430) - that said if I do switch it off there is no smell either.

I've noticed now that if I switch it off I get sweaty hands and a stuffy feel in the cabin

Maybe there is something about modern AC systems that causes this smell and you have to run AC system cleaners which might be an idea - there are some where you release the seal and leave in the cabin whilst the engine is running with the AC on

hope this helps

 

[royoftherovers]

I leave mine on all year and like Lark,do not have problems.

I have had the rotten smelly egg problem in some other cars and got rid of it by           turning the heating comtrol on high for the last 10 minutes of several journeys until all of the bacteria had been killed.

[PCM]

I doubt it's related but worth checking anyway, your pollen filter...

[matt8]

I too leave mine running all year round, and had no problems.

Then Covid came, I did not use my car for an extended period, and then the smell started shortly after.

I have purchased this but am yet to use it:

https://www.lexuspartsdirect.co.uk/parts/lexus-ux/lexus-ux-2018-present/lexus-ux-cooling-heating/lexus-air-conditioning-system-cleaner/

[wharfhouse]

Like all those above I have always left air con on auto in all my cars that had climate control including my current IS 300h and never had any problems of bad smells in any of my cars. On one BMW I had a case of windows misting up once with air con on which was diagnosed as a blocked drain - garage blew it clear and all was well from then on. Maybe worth getting an air con service where they check drains and do a good disinfect of the system (or do it yourself) then leave air con on auto from then on and see how it goes. 

[steve2006]

I also leave my AC on all the time but also use an aerosol cleaner annually. The ones I use are set off sitting on the rear transmission tunnel with the AC set to fully cold and all vents open.

[Jayw13702]

About 3 weeks ago I bought a fogger.

It runs in the car for 5 mins, leave the ac on and on recirc.
After 5 mins switch the machine off, leave the ac on for another 20 mins and allow the air to circulate.
After 20 mins open the doors and let the remaining smoke out, the ac ducts should now be cleaned/disinfected
I’ve noticed the ac smell has disappeared and also the general smell in the car is a lot cleaner






Sent from my Iphone using Tapatalk

[Bardo]

Thank you everyone for the advice. I think I'm going to definitely use the a/c on auto more, then run it on hot once the weather cools down and change the pollen filter. The Lexus air con cleaner looks like its worth a punt, will get it up on ramps to locate the drain holes, hopefully this month. 

If any one has any recommendations on which interior smoke bombs are good then please let me know.

@Jayw13702 may I ask which fogger you have? Looks like the smoke thoroughly goes everywhere in the cabin!

[chris1601]

Not running the AC does NOT cause mould/bacteria. Running the AC full time, leaving it (the evaporator) wet and then left to stand (parked up for a few days) can cause mould/bacteria to form. Typically in summer when its sat, all nice and warm and moist (oo-er). Provided the evaporator is dried out after a season of regular use by not running the AC and just using the fans, it should remain odour free. I don't run mine during winter (except a few minutes every few weeks to keep the seals healthy) and never have nasty smells. If your car is going to stand idle for days at a time, then dry the evaporator out by running the fans only for 30 minutes or so and you shouldn't need the disinfection maintenance.

Note that this is not specifically a car issue. All air conditioners suffer the same problem of moisture on the coils. The reason why most believe leaving their car AC on full time is once the evaporator is cold, it masks the smell of the presence of bacteria. Turn it off and the smell comes back, as you have found. The key is avoiding leaving those coils wet for long periods of time. Hard to do in summer but come autumn when you don't need cooling anymore, it's much easier to dry out. FYI I never have trouble with misting windows ever with the AC off provided the coils are dry.

[Bardo]

Cheers @chris1601

I'll park it in the drive with engine on, switch the heating on max heat, leave a/c off for 30 mins to see if that makes a difference. 

Do I need to have the A/C switched on for hot air to circulate around the evaporator? Also, do I keep the recirculation switched off? 

If this works without any maintenance then I'll be chuffed! 😀

 

[chris1601]

If the mouldy smell is there I think you'll need to use one of the fogger products first but give the heat trick a go first as it's basically free 🙂

No, you don't need the AC on, the air always flows through the evaporator whether the AC is on or off. Recirc on or off doesn't matter either, although it may help to further raise the temperature at the evaporator if you do recirculate. If you can get the heater outlets to 60c, that'll help.

[royoftherovers]

Just read this and decide what is appropriate for your smell.

https://www.honestjohn.co.uk/search/?type=Question&q=air+con+smells

[Bardo]

Thank you @royoftherovers

Much appreciated.

[NemesisUK]

In all my years of driving cars with aircon I have never suffered 'the nasty niff'. 

I tend to set the climate controls once on acquiring the car and rarely change them, a/c is always permanently on.

These system have definitely become more 'intelligent' over the years. My Mercs knew when the car windows were open and would adjust the airflow accordingly. I now read my Lexus has a 'neural network intelligence' running the show! Well must admit it's doing a damned fine job and in virtual silence. My Mercs' air ducts used to creak and crack horrendously after being parked in very hot weather as the a/c cooled the interior when setting off. My RC, not a murmur, class!

[Jayw13702]

Thank you everyone for the advice. I think I'm going to definitely use the a/c on auto more, then run it on hot once the weather cools down and change the pollen filter. The Lexus air con cleaner looks like its worth a punt, will get it up on ramps to locate the drain holes, hopefully this month. 
If any one has any recommendations on which interior smoke bombs are good then please let me know.
[mention=60933]Jayw13702[/mention] may I ask which fogger you have? Looks like the smoke thoroughly goes everywhere in the cabin!

I have this one


https://www.valetingproducts.co.uk/product/fog-it3

I have done all the cars in my family and a few of the neighbours as well


Sent from my Iphone using Tapatalk

[matt8]

Does anyone know where the ducts are on the Is300h and how to check they are clear?

[Jandb]

I have this smell all the time. Have treated with some evaporator core cleaner (access through the cabin filter with a long hose) but usually only lasts a couple of months. I think I might ask the dealer to clean it professionally to see if that helps. 
 

cleaning the ducts will not do much as the smell is actually mold sitting on the evap core. 

[royoftherovers]

53 minutes ago, Jandb said:

I have this smell all the time. Have treated with some evaporator core cleaner (access through the cabin filter with a long hose) but usually only lasts a couple of months. I think I might ask the dealer to clean it professionally to see if that helps. 
 

cleaning the ducts will not do much as the smell is actually mold sitting on the evap core. 

Try turning to Hot for the last 10 mins of journeys for next few weeks and see if that helps.

[Bardo]

Since my original post, I've taken the advice of members and I've found that that running the heating on max for about an hour really helped eradicate the foul smell.

Now when I use the a/c for cool air, I always try and switch the a/c off, heat on high for the last 5-10 minutes of the journey.

I've also disabled the recirculation mode as I found that was keeping the moisture in.

Appreciate that this isn't ideal, but if it keeps the smell at bay then I'm going to continue. Running the heater on high temperatures during the winter will hopefully also help.

[royoftherovers]

Really good to know that our advice is sometimes heeded. Thanks Hilten.

[PCM]

When I use my a/c, I always turn it off a minute or two before I arrive at my destination.

My thinking is that, give it time to take out any moisture that might condense etc...

I also, once a year, use an aerosol thing.

I never, get home, a/c off and engine off at the same time. Just habit now...

No egg smells from the a/c.

[Bardo]

Yes, drying out the evaporator definitely helps. I just need to make it more of a habit.

Out of interest, does anyone have any a/c cleaner aerosol recommendations? 

Having used the Toyota/Lexus one cited my original post, I'm really not that keen on its 'perfumey' smell.