Taking a Stand on 2007 Prius AC Mold Problem!

FJ Cruiser also has a cabin air filter like the Prius and the post #41 Mercedes.

My truck exudes water from it's A/C drain tube - never had a problem with smell until it was 8 years old. No air filter.

Edit:
Though I have not experienced the Prius issue you guys are talking about, by looking through the Prius factory service manual diagrams (see page AC-20), I'm convinced that the issue is probably that the air filter is holding the musty air in the HVAC box cavity between the air filter and the AC evaporator coil - accellerating the growth of mold and bacteria in that area. There is also no clear air convection path for hot humid air to convect through the AC evaporator while the HVAC system is not running. The path is obstructed by the cabin air filter which requires force to move air through it.

Try this test next time you replace your cabin air filter: remove the cabin air filter and take a sniff of it after your car has been parked in the sun for a while. I'll betcha a cyber beer that it reeks because it is saturated with moldy air that is trying to escape through the fresh air/recirculation intake.

If you are satisfied that repeatedly cleaning the mold out when it returns is the ultimate fix, then you're satisfied. If it were my car, I think I'd try replacing the air filter with a piece of window screen for a while just to see if that helped. The water drain tube will drain water, but it won't convect humid air out of the system.

 

Interesting take on the problem the air filter contributing to it but why does it smell great going on now 40 days after a Nu Calgon anti bac bath through the firewall? The ultimate dealer fix is the same treatment too. Thank you...I appreciate any and all contributions to this problem though. BTW, I have replaced the air filter twice...both times it was spotless. I don't smoke...no pets..detailed alot. You could eat off it. In fact I take it out every weekend and clean the little dust off it. Its do easy I can take it out in less than 15 seconds. It smells nice though.
I think ultimately Jayman is correct in its a system design problem. One that Toyota must shudder thinking about fixing.

 

The reason it smells good is because you've recently killed most of the mold, but it will eventually return. I'm just thinking that the cavity between the evaporator and the air filter isn't getting air current when the HVAC system isn't running so it never dries out, and that the air filter is the cause of that problem. The air filter requires the fan to pass air through it. So when the car is powered down, the minute air currents that allow humidity to leave the system are being blocked by the air filter - and that (in my opinion, for what it is worth) is the system design problem. Toyota should design in a solenoid controlled vent in the HVAC box to allow moist air to convect out of the system when the car is powered down if they are going to have a cabin air filter. Better yet, they could put a little solar powered fan in that vent.

I don't understand the "Variable speed" nature of the Prius AC system that Jayman was talking about. I always thought the compressor turns either on or off and there is can be no in-between. Could this be a variable duration between on and off cycles?

Oh well, I'll quit rambling. This troubleshooting process is probably a subject for a separate thread. The poor dude that started this thread wants his satisfaction out of Toyota!

 

GM had a similar problem with stinky A/C, so had a retrofit kit that allowed the blower fan to run for a couple of minutes after the car was shut down. This was enough to get the excess humidity off the e-coil and case, and keep most problems away. THeir newer cars have this feature built-in as programming

The Prius has an electric A/C compressor that is truly variable speed. You can't tell by sitting in the driver seat and driving around, it's very unobtrusive.

With the car in Park, pop the hood and the A/C makes a very distinctive soft whine that will vary in pitch as the cooling load changes. The best way to appreciate this is to come out to the car on a very hot day, pop the hood, and have somebody else power up the car.

While standing over the passenger side of the engine compartment, tell the person behind the wheel to power up the Prius and turn on the A/C, if it already isn't on. You'll hear the cooling fans turn on and then a very distinctive whine that will build in pitch, that is the A/C compressor

Some folks claim to see the "clutch" engage on the Prius A/C compressor and hear a click, that is complete bulls***. It's true on my FJ, as it is on any conventional car or truck

There are advantages to variable speed A/C. They tend to be at least 30% more efficient than conventional single speed on/off systems. In a humid climate, moisture removal is greatly enhanced. That is also the problem, the e-coil will tend to remain cold and wet almost all the time

My Bryant Evolution system at my house, and at my hobby farm, are also variable speed. The gas furnace has an ECM blower fan that is truly variable speed. The e-coil has a TXV - thermal expansion valve - to allow multiple compressor speed, and to enhance e-coil performance

Evolution Control - Bryant

Evolution® System Central Air Conditioner - Bryant

Evolution® System Plus 95s Gas Furnace - Bryant

The outdoor unit is a two-speed Scroll compressor. The vast majority of the time, the compressor and condenser fan run on Low. We got up to 94 yesterday, with nasty humidity, so towards the late afternoon it would sometimes ramp up to High

I've programmed my Bryant Evolution system for dehumidification priority. That means it will be sloppy with temp setpoint, as it will run the furnace fan at the slowest possible speed. This really enhances moisture removal and efficiency, my summer cooling cost is 50% of my neighbors with conventional systems

I've also had issues with stinky A/C at my house and hobby farm. I need to disinfect the e-coil at the start of the cooling season to keep the smell away, and again at the end of the cooling season. I've scheduled the dealer to put UV lamps in the plenum above the e-coil, this is proven to greatly reduce mold/mildew issues in e-coils

UV Lamp - Bryant

I'm wondering if Toyota can't program the blower fan to run for a couple of minutes after the car is powered off?

I agree with your assesment of cabin air filters. Overall, I prefer the use of a cabin air filter, even if that means I have to disinfect my e-coil once a year. At least on my FJ, it's quite simple to get to the e-coil: the blower motor is super easy to remove, and the blend air door is easy to access.

 

Hi Jay,

Well, this would be true if the person in question was looking at Classic which has a belt-driven air conditioner compressor of traditional design. I agree that with the 2G compressor there is no clutch (or for that matter, any moving parts) to see.

It seems quite reasonable to have the blower fan run plus open the air recirc door, upon IG-OFF - as long as that would not unduly tax the 12V auxiliary battery... Perhaps the program logic would have to require a minimum ambient temp and minimum vehicle runtime prior to shutdown (so that the battery would have had a chance to be charged up) before allowing this to happen.

Since this feature is not currently available, I suppose that a concerned driver needs to turn off the A/C compressor, open the air recirc door manually, and leave the ventilation fan on, a couple of minutes prior to reaching his/her destination.

 

I will call toyota. I have a 2007 with 47k miles and have just noticed a mildew-type smell. Although I'm in southern CA, it's been rather humid (for here) lately and I've been constantly running the a/c. Thanks to everyone's input, I now know how to proceed.

 

Patrick

If programmed in, you could also monitor the battery voltage and have a rule like off or end if 12vdcbus<12.5

I'm still unsure of the permutations with this issue. Is it dusty conditions, non-dusty conditions, ambient humidity, excess pollen, etc. Regression analysis isn't something i'm in the mood for after 3 beers

That said, I *soaked* my Prius e-coil with NuCalgon EvapFresh last summer, and it's still odor free

jay

 

I have a 2008 Prius and it has the same mold smell problem in the AC. I brought it into the dealer and they cleaned the coils (I think) which stopped the problem for about 3 months.

The car was only about 4 months old when I started having the problem. I live in Tampa, FL. which is humid, but I've never had a car with this mold smell problem.

I will call Toyota customer service.

I hope everyone does the same.

Your right, there is power in numbers.

 

Your power in numbers will never beat the cost of Toyota fixing this problem.
Thats some real numbers.

I did call the factory......they bounced me back to the dealer...dealer said if I was under 5K miles they would have done the coil cleaning for free. I bought the dealer kit but Jaymans methodology has worked so far. 2 months and pretty stink free so far.
No way around it...its going to be a regular maint. issue. I have found Jaymans firewall system to work good so far. Load up with coil cleaner...and hose away.Crude but effective. Thanks Jayman.

 

The only problem is that - for most people - it's a very difficult maintenance item. It would have been brainless for Toyota to design into the HVAC case an inspection plug/port that would be easily removed. Spray the e-coil, put the cover back on

Nope, instead we're stuck going through the firewall plug, pulling off the blower (My FJ), or sneaking out a pricey fiber optic inspection scope from work and *very* carefully drilling access holes into the case

Most HVAC in heavy duty highway tractors, such as Peterbilt or Kenworth, are designed for quick and easy servicing. Near my hobby farm, a neighbor runs a fleet of Kenworth T2000, the e-coil is easy to remove and swing aside, with all cooling lines attached. Makes for easy and quick disinfecting

Considering the cost of replacing an entire case or e-coil, I really can't see Toyota springing for too much of that before somebody is stuck paying a +$1,500 bill. Replacing the case and coil is a very short term fix anyway

jay

 

Update: My local Toyota dealership has been fantastic. They took the car and gave me a rental while they unclogged the drain and checked for mold in the AC unit. We were out of the car for three days of being in a rental, and then didn't get in it that weekend. I finally began feeling better and was able to stop the two inhalers I began needing after driving the car. I felt good as new the morning of the 6th day, and my daughter's headaches were gone. They also detailed the inside of the car, and we thought we were good to go and very excited. I picked up the car, and the headaches, burning eyes, burning sinuses and tight chest all returned. After a week of being back in the car - all three of us have gotten very ill again. I can't understand or believe it. I don't know if we are reacting to the foam-cleaner that was used to get rid of the smell in the AC unit itself. We are stumped and sad that we have to get rid of our car. None of us have allergies or sensitivities, and we consider ourselves healthy. I do have to applaud Toyota though for trying to find the mold - the Marin Toyota service manager was amazing.

Does anyone have any thoughts about what could be causing these wierd symptoms? Dry mouth and face, burning eyes, nose and throat, trouble breathing (asthma) and headaches.

Previous:
I am having a horrible problem with mold in the AC unit of my Toyota Highlander Hybrid. It has gone on for a long time and has been really tough to get someone to take me seriously. My entire family has gotten sick from it now and I am ready to get rid of this car if we can't fix it. I LOVE my car though, but it is becoming too hard on my children's health and is deeply concerning.

 

I test drove a HiHy a couple of years ago, but honestly have no clue where the evaporator coil is in that vehicle. All I can suggest is a careful inspection of the HVAC system to determine how easy it is to get to the e-coil

You could try a subscription to Toyota Techinfo or All Data to get manufacturer detailed parts location diagrams. If it's as simple as taking out the blower motor, you could try to clean it yourself

The e-coil in my FJ was starting to stink and I dropped the blower motor, forced open the blend air door, and was able to saturate the coil from inside. Another option is to trace the coolant lines from compressor to firewall, and pull out the rubber firewall plug to apply the disinfectant

I'll caution you - as I caution everybody - to never ever use household bleach to disinfect an e-coil. The e-coil has aluminum fins with copper tubing, you would destroy the coil if you sprayed bleach on it

I've provided links to the NuCalgon professional HVAC chemicals I use. I especially recommend EvapFresh, it's an EPA-registered coil disinfectant for molds, mildew, bacteria, and viruses. It provides mild cleaning too, and is safe for coils. EvapFresh is premixed in a gallon size.

Some folks have had plugged or partially plugged coil drain tubes. I'm sure you've checked for that.

I don't have time to research this right now. I got back from a business trip a couple of days ago, and am in the middle of packing to leave this afternoon for a couple of weeks.

 

Help! I've got a 2008 (9500 miles), purchased in December 2007, with this issue. I live in the Dallas area. I didnt' notice the smell until the middle of summer. It's worse after I have run the AC on recirc then park the car. Come back later or the next morning and then just run the fans without AC on. If I run the AC the smell goes away. When I run without AC the smell comes back. It's starting to give me a headache. The smell goes away or lessens with the AC off if I run the fans to draw in outside air.

I haven't noticed much water dripping under my car from the AC like other cars. My Honda Element leaves a large puddle of water while the Pruis barely makes a drop. If it couldn't drain the water wouldn't my carpet be wet?

I'm due for the next service soon and will have the dealer look at the issue. Maybe my drain line is restricted. I will call the Toyota regarding this issue.

This is so un-Toyota-like.

Kelvin

 

Kelvin

That could be the source of the funk - an automotive A/C should piddle a healthy amount of water especially when its humid outside. If you can directly compare two cars side by side, say your Element, and the Prius barely drips, something is plugged

If the drain tube is completely plugged, you'd eventually end up with water on the carpet. If the drain tube is partially plugged or kinked, water will pool in the bottom of the case - *nasty* things will grow

It's not unheard of for a new car to have a kinked drain tube. By all means have your dealer check this and hope your dealer actually cares enough to fix the problem. That includes sanitizing the coil and case with an approved chemical. You *must* kill off what is growing in there, otherwise even with the tube running clear, it will still stink

jay

 

I'm guessing I hold the record for the quickest time to observe this problem: 1.5 weeks! That's right, less than 2 weeks after I got my 2009 Prius, I got that smell.

I had it in my Camry before it, and my Honda Accord before that. I don't recall ever having it on the two VWs I owned before that, however.

Do any of you know where the recirculate-mode intake vents are, within the cabin? I ask because I was able to kill the mold on my Accord by blasting a few cans of Lysol into the outside intake vents. However, that did not work on my Camry, because its water trap is too good: Virtually all of it just sprayed down through to the floor of the garage, and almost none of it got into the AC system. However, if I blast it into the cabin-internal intake vents, it might work.

 

Ding! Ding! Ding! We have a winner! Your the fastest reporter of this problem. :hurt:Go directly to your nearest Toyota dealer for your grand prize!
Basically they have a kit consisting of a spray anti funkalyzer they spray into the drip tube of the e-coil below which fills the e-coil housing up with anti funkalyzer. See pic below. Its free up to 5k miles then your on your own...meaning they'll drill you every time you need it. I just bought the kit over the parts counter at Toyota for $35 and will do it myself very soon 'cause I'm at 11k..

 

By the way, I also do (as I did with the Camry) make a point to take the air conditioner out of recirculate before I shut off the hybrid system, so that the water can drain out. I guess it didn't help much in this case...

That's good information about the mold killer kit; thanks. Could you very quickly describe where the "drip tube" is? Is that where the water drains from (i.e., at the bottom of the evaporator housing)? Maybe I should just ask a service tech to demonstrate it.

 

Your information is incorrect. Recirc is NOT the default setting. The Prius will initially run A/C in Recirc when Auto A/C is switched on and then change to fresh air about a minute later.

Get your facts straight before you post.

-Dave

 

Not sure what you mean by "so that the water can drain out" but basically all your doing when you leave it in fresh is the door that steers fresh air into the e-box is left open so some fresh air can get in there and dry the coils as opposed to leaving it in re-circ which leaves the fresh door closed. It does help a little as I have been doing it religiously now but the e-coil still has a problem. But its a big problem with the Prius. Please search my old posts and Jaymans responses to it. But bottom its not a clogged drip line causing it. Clogged drip lines only cause smell because the e box has overflowed and now has soaked your front carpet. Clogged drip lines are not the issue with this car and smell. My car started stinking just 2 months after purchase and always had good water flow out of the drip line.BTW, in any car you've ever owned in all your years of driving did you ever have a clogged drip line?
Anyway the dripline can be found: Behind the pass front tire about 2.5 feet directly in. Small black rubber hose dangling at a 45 degree angle.
Its a shame because its really the only issue I have with this car and living in Florida you have to use the AC all the time. The car has been perfect otherwise. Good Luck.

 

What a GREAT THREAD ~ Had no idea there could be an issue like this in our vehicles. Mold is a BIG DEAL ~ People can get very sick from certain mold spores. Appreciate all the information and approaches shared in this thread and will be having the mentioned areas checked at every oil change as well...sure hope to avoid this issue. Thank You to "Walk the Walk" for starting this informative thread and the education provided by all who have contributed.... Erin