[Stiggy]

About three months ago I picked up a 2009 Ridgeline RTL with 22,820 original miles on it. I had a 2007 company-provided Ridgeline that I gave up when I switched jobs in 2009 so I am very happy to be driving one again. The only significant issue I have with it is that there is an overwhelming mildew smell produced whenever I turn on the A/C. Unlike some, I prefer to not have the A/C on whenever possible as I prefer a more humid cabin atmosphere if possible. Obviously, I use the A/C when needed to defrost the windows or to stay comfortable when the temperature and or humidity outside are too much. Does anyone have experience with this problem? Should I start with replacing the cabin filter? Where is it located? Is there a drain in the air circulation ducts that may be clogged? Any help would be appreciated.
Thanks in advance.
Stiggy

 

[Carsmak]

As long as your not finding any "damp" areas on the floor, or under the floor mats front, and under the seat in the rear, then I'd start with a new Cabin Air Filter, it's located behind the glove box and can be replaced in about 5 minutes. There is a part which during replacement is often dropped to the passengers floor mat. The link below is very helpful to either have on a tablet when doing the job or study just before doing it. Most go with the Cheapest CAF from Rock Auto, Amazon or your local parts store. There are both Plain and Charcoal impregnated, and possibly some with baking soda which may assist in "clearing the air"

Read this thread for Cabin Air Filter Replacement

If that doesn't help, I'd get another cheap CAF and a can of Automotive HVAC Deodorizer / Odor Eliminator. I've used something like this on my Honda Del Sol and was amazed with the results, when it was the wife's daily driver while we were down to 2 vehicles a few years ago. The Del Sol has no CAF so I also partially dissembled the HVAC and "Pushed" air in the opposite direction of typical flow, but it didn't help near as much as the Deodorizer and was like a 5 min job, before I tried that I was considering removing the dash.

Automotive HVAC Deodorizer / Odor Eliminator

 

[Flyboy]

Check to make sure it's draining correctly as well. Somethings making things wet.

 

[Carsmak]

Check to make sure it's draining correctly as well. Somethings making things wet.

True, water going down the windshield, should drain out the back of the front two mud flaps. IIRC

 

[Flyboy]

True, water going down the windshield, should drain out the back of the front two mud flaps. IIRC

Well in this case I was speaking of the AC drain. :nerd:

but good point.

 

[speedlever]

a can of Automotive HVAC Deodorizer / Odor Eliminator. I've used something like this on my Honda Del Sol and was amazed with the results, when it was the wife's daily driver while we were down to 2 vehicles a few years ago. The Del Sol has no CAF so I also partially dissembled the HVAC and "Pushed" air in the opposite direction of typical flow, but it didn't help near as much as the Deodorizer and was like a 5 min job, before I tried that I was considering removing the dash.

Automotive HVAC Deodorizer / Odor Eliminator

How does this stuff work? Just shoot into into the A/C vents with the system off?

 

[Carsmak]

No shoot in it the intake with the system running at full throttle. Surprisingly better than I expected. YMMV

 

[speedlever]

It makes sense to remove the cabin air filter and shoot it in there with the fan running on max. I presume that is what you mean?

 

[S.T.U.V]

Go get yourself a product called OZIUM should be able to find it at any auto parts store. Completely remove your cabin filter so it doesnt filter the spray. Get the biggest size and spray it in you air intake which is in between you hood and the windshield. Make sure it is on highest fan speed and not on max a/c(so it sucks outside air) but on full cold. Spray the whole can into the vents. Then let your truck sit for a few hrs in the sun
(off of course.) Replace cabin filter with newThat stuff works really good and kills mold spores etc.

Another thing to check if put the truck on full max everything. max a/c on and recirculate and make sure after about 10 ish minutes or so you see water dripping under neath the front end. Dont remember where it exactly drips but I think more on passenger side. If it drips then the a/c system should be draining fine.



You could do it with the cabin filter out and spraying it into the cabin filter slot...but you would be missing alot of ducting doing it that way.

 

[Carsmak]

I think if I had a CAF, like Our RL, I'd be inclined to do it with it installed (a cheap one) and after done. Throw it away, replacing it with a new one after.

 

[FTM1]

I would guess you do not have the yellow recirculating light button on constant operation of the A/C. The fresh air button should be on most of the time. Just asking because some people do this.
Now if you need a product try the BG Frigi Fresh and or BG Frigi Clean
There are tons of youtube on the products and how to use them.
Also you can find one of their shops to do it for you.

 

[speedlever]

Or, you could use this product (but then wish you hadn't!)

Robot Check

 

[48218]

My wife's Camry has that issue. It has auto climate control, which she uses most of the time. The ACC essentially always keeps things on recirculate any time the A/C is on (which is most of the time here). I find on the Ridge that so long as I do two things, I can avoid this odor essentially always:

1) Keep the system bringing in fresh air the vast majority of the time, and
2) Turn the A/C off at least a few seconds before shutting the engine off.

Maybe it's just coincidence? Nevertheless, I only get this musty smell for the few seconds after A/C shut-down and before the evaporator is dry.

 

[Stiggy]

Just want to follow up on the mildew smell in my '09 Ridgeline: After initially posting this thread, I replaced the CAF. The old one was very dirty and had what looked like mold on it. That helped for about two weeks and then the smell returned. I also noticed that there was no puddle of water on the garage floor after driving with the AC on indicating the condensation drain line was plugged. I brought it to my local mechanic who is quite good. He unplugged the drain and treated the system with one of the duct cleaning sprays available. That helped for maybe three weeks. I brought it back and he treated it again. That lasted most of the summer and into the fall. Over the past month, the mildew smell has returned. I will check the CAF and treat the system with the duct cleaning sprays myself this time. I have to think there is some sort of sediment or debris somewhere in the duct system that is serving as a medium for mold or mildew growth when it gets wet from normal operation. Then it is just a matter of time before something starts to grow and smell. I also think that the best way to solve this problem is to disassemble the duct system including any enclosures that exist around some of the components of the system and clean everything thoroughly with bleach. Has anyone out there done this? Or know how difficult it would be to do? I'd consider doing it myself if it can be accomplished in a weekend. Thanks! Stiggy

 

[dorkygrin]

Did anyone ever reply to your request on how to completely disassemble and clean the evaporator and related air vents? I'm interested in doing this too. Might be a really big job, but there I'm unable to find any solid info on really digging in.

Thanks!