Smell when AC turned off

[penguinpaul]

I've had my 2011 CT for around 3 or 4 months now.
One issue I have, is that turning on the fan with AC off results in a stale smell.
I get it in the few seconds waiting for the AC to kick in, and I also get it if I turn the AC off and just have the fan.
The moment I switch AC back on, the smell disappears.

I've tried leaving it on max heat setting blowing hot air for 15 minutes, and I've also tried an Autoglym aircon deoderiser (the type that empties the can while the car is set to recirculate).
Cabin filter is brand new.

Is there any reason why it might only smell when AC is off? Doesn't matter if it's set to outside or recirculate. It's a strange problem!
Any advice would be greatly appreciated!

[NemesisUK]

My advice is never turn the a/c off..

It adds an insignificant load and negligible mpg cost.

Leaving the a/c on permanently ensures all the system seals are lubricated and ensures the air is dehumidified, bacteria can't grow in the dry environment in the heat exchanger and duct work.. 

There really is no downside to leaving it on, let the system operate as designed in Auto mode..

[penguinpaul]

I almost always do have the AC on, but when you start the car, it takes 10 seconds or so for the AC to start working fully, so in that time you've got to hold your nose!
I thought at first it was stale air somehow being moved out of the pipes, but then discovered that the smell comes back if you switch the AC off..

[NemesisUK]

Check the a/c heat exchanger drain is clear? I've no idea where this would be on you model, guessing somewhere central, near the front of the transmission tunnel?

[rayaans]

17 minutes ago, penguinpaul said:

I almost always do have the AC on, but when you start the car, it takes 10 seconds or so for the AC to start working fully, so in that time you've got to hold your nose!
I thought at first it was stale air somehow being moved out of the pipes, but then discovered that the smell comes back if you switch the AC off..

The stale smell is due to bacteria etc so I would assume that the previous owners didn't have it on all the time.

You need to clean the system out with an air con bomb. You can do it yourself:

https://www.carparts4less.co.uk/cp4l/p/-/-/-/-/?NOR2897300&0&cc5_101&gclid=CjwKCAjwwdTbBRAIEiwAYQf_E-gwZ7XN5eG6rb2hY61GQSv6r3wDK03484aaIOi_u6fhaSVQDaol1xoCyckQAvD_BwE

https://www.carparts4less.co.uk/cp4l/p/-/-/-/-/?NOR2897300100&0&cc5_101&gclid=CjwKCAjwwdTbBRAIEiwAYQf_E_CwUUjYYUfw4Z5IBHjtmPqA1SUWNWxHLZ_gCE0TjkTLO_zKbPHt3RoC8AgQAvD_BwE

Use both products together - currently can be had for under £10 for both using code AUGUST12

However, before you splurge, check for damp as that might be the cause as mentioned above. 

[200h]

i have cleaned out the aircon drain tube on a yaris it was in the passenger footwell next to the tunnel

the amount of rubbish in there was surprising

[penguinpaul]

Thanks all, I've used an Autoglym aircon bomb that didn't help, but maybe the more specialist products are a better bet.
In the mean time, I'll look into cleaning the drain. Looks like it's easier to access from under the carpet, rather than below the car. Also looks like there's a foam cleaner designed for the job too.

[200h]

when i cleaned the drain on the yaris i used a large syringe so i could

put hot water under pressure to help remove any dirt clogging up the drain pipe

i also squirted water back in the unit in the car this loosened loads of dirt as well

i used a takeaway tray to catch the water & dirt.

 

[200h]

i have just seen this video it may be worth a shot

here is a video for a foam air duct cleaner

here is a link

 

[rayaans]

On 8/20/2018 at 3:28 PM, 200h said:

i have just seen this video it may be worth a shot

here is a video for a foam air duct cleaner

here is a link

 

I thought the first guy sounded familiar

He's a massive reviewer of headlight bulbs! 

[Rutlandlex]

Mine did this recently.  It occurred to me that I haven't had my air con or fan on at all for many weeks due to the heatwave as I like driving with the windows and sunroof open in hot weather so I just put it down to that.  I rarely use my air con because I've never been a big fan of it so I tend to only use mine for de-misting the windows when it rains or for long journeys when it's hot because of the noise with windows and sunroof open.

I went to Scotland last week and suffice to say the weather was much cooler and wetter than what I have been used to and I noticed the smell the first time I put the heater on.  Sometimes I had the heater on without air con and sometimes with and the smell has now gone regardless of whether the air con is on or not.  I know that doesn't help the OP but just thought I would share my experience.

[Ajmx1]

Hi Paul did you manage to solve this problem ? 
I seem to have the same problem now.

Thanks Aaron 

[Las Palmas]

On 8/16/2018 at 12:01 PM, NemesisUK said:

My advice is never turn the a/c off..

It adds an insignificant load and negligible mpg cost.

Leaving the a/c on permanently ensures all the system seals are lubricated and ensures the air is dehumidified, bacteria can't grow in the dry environment in the heat exchanger and duct work.. 

There really is no downside to leaving it on, let the system operate as designed in Auto mode..

All of what you write is correct in my opinion except that it is not costing fuel.

Having my a/c on all time I have 7L/100km.

No a/c I have 6.7L/100km.

Live where flat roads hardly exist and going up cost fuel, going down fills the Battery, but not giving nearly as much power as going up costs.

Decided that a/c is best to keep on and accept what it cost in fuel.

[Las Palmas]

If all the tricks here are not helping I would go to a specialist a/c company and have it done. Had bad smell in a MB 350SE and a Honda Civic. Both cars were cleaned and the a/c expert told me to always stop using a/c 5 minutes before you stop and in that time have full power on ventilation. Did that and had no smell problems.

In the CT we have now we are going to keep a/c on permanent. It is always hot here. Tried a week without a/c to see how much it would reduce fuel consume, but keeping a/c on all time is just much more pleasant.

[penguinpaul]

4 hours ago, Ajmx1 said:

Hi Paul did you manage to solve this problem ? 
I seem to have the same problem now.

Thanks Aaron 

Hi Aaron,

I rarely use it without the AC now, but it used to do it at first before the AC came through! 
That’s stopped now, so I don’t know if it’s just constant use that has cleared it out, or several Meguiars Air Con cleaning sprays that have gone through it. 
Worth a try for a tenner! I’ve been using the Fiji sunset one. 

[Ajmx1]

Excellent thank you so much I will try another air con freshener. 

[Vadim]

I used K2 Air con cleaner foam.

Helped to get rid of tobacco smells in a pre-owned car with good degree of success. Though I had to apply it twice.

To let the foam in, I removed the pollen filter and sprayed on the fan and into the duct leading to the radiators. The K2 manual also recommends to spray the foam from under the car into the AC condensate drain pipe, because it is usually the shortest way to the AC radiator inside.