Chemical/musty smell when turning on the a/c

[praetorian84]

My 2016 Ecoboost Mustang gives a weird smell when I turn on the a/c. The smell goes away after some time.
It doesn't happen every time. Happens if I used a/c the previous time and then turn on a/c or just the fan after a day or so.
I also noticed that the problem doesn't occur if the a/c was in fan mode or heating mode the previous time. The smell is NOT the sweet antifreeze type. More of a dry musty smell.

Looking for guidance here. I tried pretty much all the vent sprays such as A/C Pro and Ozium. Also tried the Mist spray service at Pep Boys to no avail.

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[Cobra Jet]

When is the last time the cabin filter was changed? It’s possible the cabin filter is filled with debris or has mold spores...

Also if running the A/C before parking car and shutting it down, turn off A/C, put your HVAC system to vents only to draw in outside air through the system. Run the system for about 5 mins, then shut off the car. When running to vents, it’s bringing outside fresh air into the HVAC ducting. This helps to dry any moisture (if occurring) within the ducting.

Here‘s a similar thread from a while back:
https://www.mustang6g.com/forums/threads/smell-when-a-c-is-turned-on.72388/

 

[praetorian84]

I changed cabin filter a month ago. And it was clean at that time

 

[NeedForGreen]

Most likely its blocked with leaves or something causing mold build up. My wife's last car had the same issue. The dealer had to blow crap out then send a cleaner through it.

 

[Elp_jc]

Like somebody said, you need to turn off your compressor a few blocks before your house, and it'd never happen again. That has been my case for decades now. As far as how to fix it perfectly, you'd need special products sprayed into the HVAC intake, to get rid of the mold in the evaporator. Hopefully somebody with experience on a Mustang could chime in and help you. Good luck.

 

[Strokerswild]

Like somebody said, you need to turn off your compressor a few blocks before your house, and it'd never happen again. That has been my case for decades now. As far as how to fix it perfectly, you'd need special products sprayed into the HVAC intake, to get rid of the mold in the evaporator. Hopefully somebody with experience on a Mustang could chime in and help you. Good luck.

This.

I learned this several daily drivers ago. First weird smelling vehicle was my '04 F150. Once I learned to shut the AC off a bit away from my house, the rank odors went away. And never were an issue again with subsequent vehicles doing the same.

 

[praetorian84]

Thanks all for the responses. Will turn compressor off next time. Did anyone try spray products up through the drain pipe?

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