[ckhbuy]

Hi -

The ventilation system in my outback, after two years of ownership, is starting to develop a tell-tale sign of some sort of growth inside of it. Most likely this is related to the fact that the car only rarely sees heat and sunshine; it sits in a covered garage at work and at home my driveway is heavily shaded. Any condensation after running the A/C probably just sits in there allowing mold to grow. The odor seems most pronounced when I run the A/C during the three days of summer we have in Boston. It's really, really, really difficult to clean out such growth from ventilation systems in cars (same thing happened to my last car) - are there any tips here from the experts on what to do to mitigate or even clean this before it gets really bad? Any good access points in the Outback's ventilation ductwork for swabbing the surfaces down? Or do I have to remove the bumper......

Christopher

 

[Shadow 1100]

Replace your cabin filter, in your glove box, good place to start. Do it your self Dealer wants $100. plust the cost of filter......

 

[ckhbuy]

Thank you for the suggestion. I replaced the cabin air filter recently - the old one was fine, just some grey discoloration from dust. I think the problem is deeper down in the ventilation system.


When my old car had a similar issue I took it to the ClicknClack CarTalk garage in Cambridge. They basically told me to live with it but sprayed some aerosol inside to either mask or minimize the odor. The smell came back in a few weeks. Oh well.

 

[upflying]

Several blocks before arriving at a destination, I shut off the AC and run the fan on high to dry out the evaporator and related plenums. No stink yet in any of my vehicles. This is especially important in high humidity climates. Incidentally, AC is also operated during the winter when you select defrost.
Warmth, darkness and moisture offer prime breeding areas for mold.

 

[OBnube]

Are you getting condensation drainage on the ground when you run the AC? If not the drain tube could be clogged causing the water to back up into the cabin onto the carpet high up in the footwell.

 

[Robert.Mauro]

Thank you for the suggestion. I replaced the cabin air filter recently - the old one was fine, just some grey discoloration from dust. I think the problem is deeper down in the ventilation system.


When my old car had a similar issue I took it to the ClicknClack CarTalk garage in Cambridge. They basically told me to live with it but sprayed some aerosol inside to either mask or minimize the odor. The smell came back in a few weeks. Oh well.

Try a cleaning spray that's designed to kill what's in there (along with masking the odor). Ozium and various Lysol brand stuff supposedly works well (though I've never sprayed them directly into the air system of a car). Then, doublecheck the cabin and AC filters and see if they're still mold/mildew free.

I'd also use the steps recommended by upflying, as well as check the drainage systems as recommended by OBnube.

HTH,
Rob

 

[ckhbuy]

Thank you, these are very good suggestions and I'll act on them. Could someone indicate where I should look for the A/C drain under the car? I don't think I could identify it easily.

 

[plain OM]

It's a small hose coming out of the lower right side of the firewall (separation between the engine compartment and the cabin), behind the right front wheel and slightly toward the center of the car. This post (http://www.subaruoutback.org/forums...-footwell-accesing-evaporator.html#post136856) has a photo of the hose on my 2007, and your's should be similar if not exactly the same.

I believe auto parts supply stores carry a spray that is designed for the smell issue, which is often due to growth of mold.

upflying's suggestion is one I follow as well. In addition, I try to avoid running the AC with the mode switch set for "recirc". When outside air is being drawn in ("recirc" off), air pressure in the duct after the fan is higher than outside, and this forces some air down the drain hose, helping to keep it clear and pushing accumulated water out. But when using "recirc", there can actually be a negative pressure in the cabin due to the flow-through vents at the back, and this can draw air in through the drain hose. (Most likely with windows closed and at higher speeds.) Dust from the road can be pulled up the hose, mixed with the water from the evaporator, and form a clog in the hose.

As was noted, when the AC is operating, there should be water dripping down from the hose, especially in humid conditions. Another test of the hose for blockage is to turn the heater fan on high, mode not on "recirc", block as many outlet vents as possible, and then check at the end of the drain hose. There should be a fairly noticeable flow of air.

 

[ckhbuy]

An update:
since posting in April I have very diligently followed upflying's advice about "blowing out" the ventilation system with A/C off and fan on high starting round about 2 blocks from my house on the way home. My goodness, the change is dramatic so far. I don't want to jinx it, but the odor has gone away to the point of barely being detectable! The idea, I believe, is to dry out any internal condensation that might have occurred due to running of the A/C system during a trip. When you kill the A/C switch, within about 10 seconds one can detect the change in the humidity of the air as it passes from dry....to very very moist....to finally that of the ambient humidity outside. I do the exact same thing when I use the defroster, since that triggers that compressor as well.

Thanks upflying - potentially a fix that costs nothing and doesn't really take up any time!

 

[Novablue]

Hmmm. Very interesting. I'm glad you found a solution to your problem.

"Mold" usually needs 3 things to grow: stagnate, regular supply of moisture, food source. Since Mold can form on dust we usually ignore the food part. I live in WA so it's hard to imagine your situation but given that the outside air is so drastically different from the AC air this all makes sense to me.

 

[4wheeldog]

Hmmm. Very interesting. I'm glad you found a solution to your problem.

"Mold" usually needs 3 things to grow: stagnate, regular supply of moisture, food source. Since Mold can form on dust we usually ignore the food part. I live in WA so it's hard to imagine your situation but given that the outside air is so drastically different from the AC air this all makes sense to me.

I live in NM........What is this "Water" that you speak of?