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Musty Smell From AC Vents

40K views 38 replies 24 participants last post by  CAM1973 
#1 ·
Hey guys,

I've got around 1700 miles on my Latitude and I've just started noticing for the first 5-10 minutes or so after I start it up I have a really musty mildew smell coming from the vents. Usually running the AC for a while eliminates the problem, but then then if the vehicle sits for several hours it starts all over again with the stale mildew smell.

Is anyone else having this issue?
 
#2 ·
First, I'd check to be sure the evaporator drain is properly draining. You should see a small puddle of water under the car after running the AC for a while (if it is a humid day). The drain is located on the right side of the center stack near the left foot of the passenger (under the carpeting). There has been at least one case reported here that the drain hose was missing completely.

If the drain is functioning properly, one trick you can try is to turn off the AC during the last two or three miles of your drive and open the system to outside air. Turn the blower on high. This will help to "dry" any moisture in the evaporator somewhat. Natrually, the longer you can end your trip with un-cooled air, the dryer the AC system will be when you park it.

Residual moisture in the evaporator sitting in a closed car eventually leads to mold problems and that musty odor.
 
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#9 ·
If the drain is functioning properly, one trick you can try is to turn off the AC during the last two or three miles of your drive and open the system to outside air. Turn the blower on high. This will help to "dry" any moisture in the evaporator somewhat. Natrually, the longer you can end your trip with un-cooled air, the dryer the AC system will be when you park it.
This
 
#3 ·
I did peek under the panel in the center stack and my drain hose is there and there doesn't seem to be any water leaking into the cabin from what I can tell. Everything seems fairly dry. I didnt run this AC at all yesterday and when I got in the car today there was no musty smell. But I did use the AC on the way to work and when I got in my car at lunch it smelled musty again for about five minutes. I guess I'll have to take it into the dealer and find out for sure if it's draining correctly.
 
#4 ·
I would definitely say that it's a good idea to bring your vehicle to an FCA dealer, Broc_Savagewood. I haven't come across any TSBs for this concern. If you would like assistance in scheduling an appointment, please feel free to let me know. Either way, keep us posted!
 
#5 ·
Update: I called up the dealership where I bought my Renegade and the service adviser told me that the musty smell is a pretty normal thing among all makes and models of cars. I'd never experienced it myself in any of the other 6 vehicles I've owned in my lifetime. (85' Chevy Monte Carlo, 97' Cavalier, 97' Nissan Wingroad, 95' Jeep Grand Cherokee, 2013 Dart SXT) So I called up another Jeep dealer and they scheduled service for September 4th. I took the vehicle in and in about 90 minutes had it back free of charge, they detected no problems with AC drainage and performed a cleaning service on the HVAC system which replaced the musty smell with a fresher cleaner scent. It's only been a few days and I've just began to notice the musty smell creeping back in. Not sure what to do at this point as there is no identifiable problem according to the service technicians. Time will tell.
 
#6 ·
Just out of curiosity, how do you run your HVAC?

I've gotten musty smells in other cars, but that was usually as they aged and the drain hose would get plugged with crud. Cleaning it out usually helped.

However, I've noticed something odd with my renegade. I've been running it in recirculating mode rather than with fresh air and haven't been noticing a musty smell at all. As the evenings around here have been getting cooler, I've been moving out of the max out the cooling mode, and I get the musty smell for a bit when I switch to fresh air input.

My guess is that moisture/condensation is building up someplace on the fresh air intake side of the system.
 
#7 ·
I've been running it less lately as well, but in the middle of the summer I was running it mostly in recirculate mode. I found that going into open vent mode and running the fans only for a day or two tended to ease the smell, but as soon as I'd use the A/C at all that musty smell would come back for a few minutes the next time I started the vehicle.

At first I thought maybe something was building up around the HVAC air intakes due to being able to smell the wiper fluid when you use it. That was one method I used to quickly clear the musty smell, though replacing it with a solvent smell isn't a vast improvement.
 
#8 ·
I also struggle with that moldy smell. Yes, it is better when I haven't been on recirculate, but still smells really bad. I've never had a car do this before either. I also think my wiper fluid reservoir has a leak. I had a huge puddle when I filled it even though I didn't spill any. My brakes also squeal like they need replaced. My dealer is about an hour away so I've been trying to wait until my first oil change to have everything addressed.

Anyone have a good link to order touch up paint?
 
#10 ·
I took my Trailhawk to the dealer for the same issue. They just sprayed Lysol in the air intake vent while the vent is running to help kill the bacteria causing the mold/musty smell. It works for a day or two but I find myself spraying it a couple of times a week. I have never had this with any other car. I love my Renegade Trailhawk otherwise. I hope someone can find a permanent fix as I am buying Lysol more often...
 
#11 ·
Surely there has to be a way of a) preventing it and b) if it does occur, a permanent solution to eradicate the smell. Obviously spraying Lysol is only a temporary fix. I have had cars in the past with air con, including classics and I have never experienced any unpleasant odours with any of them.
 
#15 ·
I have worked in the industry for 30 years. The mildew smell is caused when the A/C is run in recirculation mode and fresh air does not circulate enough to dry out the condensation built up in the evaporator system. When you park the vehicle just flip it to fresh air. It may take a few days if you have had the situation continuing for a period of time but it should clear up.
 
#17 ·
Another thing worth mentioning may be that once you got mold, mildew or fungus, they are very hard to eradicate, because some spores ted to survive in some nooks and grannies and they will procreate (It's all they do).

Like two people have already pointed out, I would advise turning the A/C off and to get fresh outside airflow going for the last few minutes of a drive to give the evaporator a chance to dry. Prevention is easier than dealing with infestation.

Also, if you smell a persistent mildewy odor, remove, inspect, and based on what your eyes and nose tells you, replace the CAF, because it is a common breeding ground for tiny nasties and a source of malodor. After all, the CAF traps all sorts of airborne contaminants (particles, bacteria, mold, funghi spores, viruses, pollen, dust, before they get into the cabin. It's an orgy in your HVAC. If you can get an activated charcoal-activated CAF, they do help eliminate all sorts of odors that you otherwise can smell in the cabin (diesel fumes, skunk, Dior Poison etc).
 
#20 ·
RE-read post #2 in this thread; especially the second paragraph. Get into the habit operating the AC in this manner, and you will reduce or eliminate musty smell problems.

Neither my Renegade or my Challenger have a musty smell.
 
#22 ·
It happened in my 2012 Challenger but not my 2015 Challenger. You really shouldn't have to turn your AC off 3 miles from home in a brand new car just so it doesn't stink like a gym sock. I tried switching it to outside air and air with no AC but it still smells bad. I do not see water under after I shut the car off which I think is the problem.
 
#23 ·
I completely agree that you should not *have* to turn off the compressor. But that isn't reality. The fact is many makes and models are afflicted by this problem. But rarely do any of them have a permanent fix. The extreme that most will go to remove the odor is to clean out the evaporator core and spray in some anti-fungal chemical. But that will only last for so long. My experience has been that drying out the evaporator before shutting the car off is a much more effective long term solution. And you have to make it a habit. You can't just do it every once and a while. And if your mold/mildew problem is too severe, no amount of drying out the evaporator will fix it. It will have to be rigorously and throughly cleaned first. Maybe the Renegade will be one of the rare exceptions and a permanent fix will be developed and implemented.
 
#27 ·
I had a similar problem on my Latitude after a cold snowy mornig when the mud and grass under the snow made for a fun exit. Mine was more like a burning smell. It went away after a week and I'm wondering if something climbed in the truck to stay warm and died. When I checked under the hood the smell was strongest out of the Driver's front fender
 
#29 ·
the evap is getting wet like it should ,
but when u leave your jeep its soakin wet ,and getting hot - mildew mold an the such love this .
as said let it run without the ac before u get to your location

this will dry the coil and keep this at bay

--- if its to far gone - u can always get the coil cleaned by a pro
or spray Lubegard Kool-It Cleaner or any evap coil cleaner , Kleen Air-Air Conditioning Cleaner & Purifier, or go the cheap way use lysol will work just the same but not as strong

this will kill the bacteria an mold an such - u may have to repeat this one more time in a week or two depepnding if it comes back , an how bad it is

pull the filter
run the ac
spray 45 seconds your choice of coil clean
then spray 30 seconds with the heat on

open the windows run it 10 min with the filter in place , with the heat on high
put it all back together
should help kill all the junk
u can use other coil cleaners that foam up and kill everything fast, and remove dirt, but they get messy as hell and are better for the pros to do ..

go look at your house window units - im sure u will see aloooot of mildew and junk on the evap coil or vents .. thats why its always good to clean your coils yearly .. runs better, cooler an quiet
and your not blowing this crap in your face
 
#30 ·
Smells like Urine in my AC 2016 -15k miles

Hey everyone. I have been reading about what you all have had as well. I see that some people have possible solutions. I just went to the dealership and paid 100.00 for a new Cabin filter and some type of spray. They said it was not covered in my warranty. I just started the car again 24hours later and the smell is still there. They said if it stays there that they will look at trying to replace something else but they said they need to figure out what part it is. When they had it at the dealership they said they never could smell it. So this is super frustrating. Can someone tell me exactly what I can tell them to replace. The urine smell is only in the mornings and evenings after the car has been off. I run my AC on auto and sync. I have a 2016 renegade 15k miles. Thanks in advance.
 
#31 ·
Hey everyone. I have been reading about what you all have had as well. I see that some people have possible solutions. I just went to the dealership and paid 100.00 for a new Cabin filter and some type of spray. They said it was not covered in my warranty. I just started the car again 24hours later and the smell is still there. They said if it stays there that they will look at trying to replace something else but they said they need to figure out what part it is. When they had it at the dealership they said they never could smell it. So this is super frustrating. Can someone tell me exactly what I can tell them to replace. The urine smell is only in the mornings and evenings after the car has been off. I run my AC on auto and sync. I have a 2016 renegade 15k miles. Thanks in advance.
It's mildew in the area that houses the evaporator coil or the heater core. If you want the best way to get the smell full zorch form the get go, turn on car, set fan to about 3/4, put the car in defog mode, turn the heat up past 3/4. AT that point the air coming through is running over both the evaporator coil AND the heater core. The whole pipeline is open, and blowing up by your face. IT also means the AC can't chill the air enough to suppress the odor, and the heater core can't dry things out and suppress the odor.

The mildew foam should offer at least temproary relief, but you need to inject enough of it while the baffles are set to give the foam access to where the mildew is.

Your service people don't smell it because they either didn't give it enough time, it'll take a couple minutes of actually operating the car to get it full zorch in my experience, OR (and more likely in my opinion) they are just lying because the real answer is the place with the problem isn't really fixable. It's sold to them as a ~$1200 module, and unless FCA says yeah they'll pay, nobody wants to pay for it. Best case in the latter, is they are setting up for a best case argument to FCA fro warranty.

With the push for efficiency, this is an increasingly common problem. The manufacturers need to do what lexus did and put a UV light in the HVAC path and run it for a few minutes on start up.
 
#32 ·
After changing the pollen filter, getting the engine up to temperature and going for a run
with the heater whacked up to max, recirc off
and all the windows open for at least 10 minutes
every few months normally keeps the dreaded smell at bay.

I think Comma do a "fogger" style treatment where
you put the A/C on full & recirc and then set the
can off and shut the door and leave it to do its
job.
 
#33 ·
This has been known about for a while with the HVAC as its the same system used in the Alfa's and Fiat's which are aplenty this side of the pond .
Presuming the odour is an offensive nearly fishy type smell the best cure as already mentioned earlier is to run the heater at full heat for ~ 30 minutes ( preferably with an already warm engine ) and open all vents while on your drive .
Did'nt have this with my last Alfa G but have had it in my wife's car , once done it didn't re-occur for the next 2 years she had the car and had same issue with a 147 many years earlier .
Don't waste time and money on " air con conditioning " products , they just mask the issue for a few days but don't actually kill the mould .
 
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