(2016.5 Touring) Weird smell from vents (not cabin filter related)

:
16.5 CX-5 Tour/AWD
Hi All,

I have this issue with my 2016.5 Touring that appears to only be very noticeable when the heater is on. I do notice something with the A/C as well but that's only if I switch from the heat to the A/C. Here's what I can describe the smell:

Heat:
  • Chemical
  • Sweet
  • Consistent
A/C (When switched from heat to A/C):
  • Minty
Facts:
  • Don't see any coolant leaks anywhere outside vehicle or leaks on my floor at all
  • Replaced the cabin filter 2 months ago so I don't think this is it
  • Issue only occurs whenever it's cold because that's when I turn on the heat
  • The smell occurs with/without the recirculation mode
  • I do see some dried white stuff around the coolant reservoir cap area but that could be because I have the coolant topped off above the max line a bit
  • Smell has been ongoing for about 2-3 years during fall/winter
  • Tried spraying lysol into outside vents and doesn't help
  • Tried using klima kleaner to evaporator core and doesn't help
  • Heat temperature feels fine when it's on
  • The smell does appear to be coming from the engine area (passenger area) but hard to say
  • Have tried to air the car out every time and the smell still remains
Conclusions:
  • Tiny coolant leak/defective heater core maybe?
  • Defective radiator cap causing coolant to steam?
I was wondering if anyone has had this issue before, it's driving me nuts because I enjoy driving the car but this issue sometimes makes me consider trading it in for something else. It's very hard to diagnose.
 
Last edited:
:
2014 Mazda CX-5 GT AWD w/Tech
Maybe put a dryer sheet on top of the cabin filter. If a smell is going to be coming in, at least it'd be one you selected!
 
:
CX5 GT
try this, turn to coldest setting with ac on, run fan on high and recirculate option for air flow . any smell?

then

turn on warmest setting and no ac , run fan on high and recirculate option for air. any smell?

chemical and sweet, may be coolant indeed?
but sometimes it could be stale smell from ac as well, although its like dirty muddy socks that one and when ac is turned on initially.
 
Last edited:
:
16.5 CX-5 Tour/AWD
Maybe put a dryer sheet on top of the cabin filter. If a smell is going to be coming in, at least it'd be one you selected!

LOL, that's a good option but I would like to get to the root cause of the smell. I went to the dealership today and they tried to sell me a $69 cabin filter + $100 to find out the root cause of the smell, a.k.a spraying ozium most likely to "reset the smell."
 
:
16.5 CX-5 Tour/AWD
try this, turn to coldest setting with ac on, run fan on high and recirculate option for air flow . any smell?

then

turn on warmest setting and no ac , run fan on high and recirculate option for air. any smell?

chemical and sweet, may be coolant indeed?
but sometimes it could be stale smell from ac as well, although its like dirty muddy socks that one and when ac is turned on initially.

Yes, for both there's still a smell. I usually have my A/C on with the recirculation turned on since I don't want to smell the exhaust from other vehicles. It's actually quite hard to describe the smell but I just tested it again a few minutes ago with the heat on max and recirculation turned on and it does smell kind of weird like a stinky smell.
 
:
CX5 GT
well in that case what I would do if it was me would be first the following below.
Which is minimal cost and some labour time from you mostly.

Check for trash under the windshield covers (outside where the car gets air from),
Check cabin filter,
Check the ac drainage (there are older threads on the forum with pictures)
Try to clean the evaporator that is inside the cabin after the the cabin filter and blower. They sell special cleaning/disinfecting sprays for it. Mazda also has oem but its expensive. There was a Mazda service bulletin how to clean the evaporator from musky smell some time ago.

And last would be the heater core.Hopefully its not that vecause its a pita to change that.

here is the diagram of air flows, as you can see the evaporator is first in the flow, even if ac is off.

ac5uun00000335.gif
 
Top