2004 Infiniti G35x air conditioning smell

smells

#1

Help unstump this chump! Our family has a 2004 Infiniti G35x that we purchased used in February 2007. Since the onset of summer, the AC has seen good use…but…it absolutely stinks after you switch over to the “fresh” air. Let’s just say it smells like a cat spent a couple of weeks in there without a litterbox (#1 not #2!).



I called the manufacturer’s customer service division in hopes of getting the answer from the source. They had no suggestion other than to speak with the dealer…thank you for nothing! So the dealer gave us a suggestion that our microfilter was “mold” infested as well as our ductwork…so they suggested we replace it (we did) and then use Frebreeze while the air intake was on AC full blast. Then after 10 minutes turn it off and wait a few minutes before switching the AC to the fresh air intake mode. Well, this worked for about 1 day and the stink was back with a vengence. Then they resorted to “oh well” and go to the auto store to get this pressurized can of alcohol based duct disinfectant to forever KILL the bacteria. Well, surprise surprise, that worked for about two days.



The stump is why does this smell only come out after using the AC and not during? If it’s there in the ducts then why the heck doesn’t it smell 24/7 even in wintertime use of the heater?



Please HELP!

Sincerely,

Cat “Bit”


#2

I suspect the fresh air intake vents have critter crap in them.

Birds sometimes have an uncanny bombing capabilities and some remains may have been washed into the vents with rain/car wash/etc.

These vents are located right below the windshield glass usually covered with a plastic vented shroud.

Why no smell in winter? Perhaps because the temp is cold.


#3

I agree with RR. I would only add the possibility that the A/C condensation drain may be clogged as well. The drain is usually a small rubber hose that comes out under the car right in front of where the passenger’s feet usually are found. Some compressed air or string trimmer line can help clear it.


#4

You have something growing on the evaporator coils. While the coils are cold, the volatile organic material that you are smelling is not so volatile. As the coils warm up, the material boils off and you smell it. After a while, it is all gone (winter) and you don’t smell it at all.

I have posted this here before. My apologes to those who must see it again:

You are not alone. A lot of people complain about this. I am very susceptible to mold allergies so I have done some research. I think you are on the right track by looking to clean. Most people are looking for a magic spray that will fix the problem and lots of people suggest this approach – Lysol or similar stuff sprayed into the AC system with the blower running and the windows open. This may work for a time, but it is probably only a temporary solution. It will kill existing bacteria and fungi, but they will start to regrow as soon as the culture medium (crap) in your AC system is reinnoculated (immediately).

First the simple solutions. Check to be sure that your AC drain is not clogged. Another simple thing to do is when you park the car be sure to leave your HVAC system in any position BUT “off”, “max” or “recirc”. Some owners’ manuals specify this to let air circulate through the system. Try turning the temp control to full hot after parking before you shut the car off. This, in theory might circulate hot dry air from the cabin back through the evap coil by convection. Note well the “in theory”. I have not tested this theory, but it seemed to help me a little. If you live where it is not too uncomfortable, turn the AC off some time before you park, it might help dry the system out. Note that running it right before parking with the heat on is not likely to help since the heater is AFTER the AC coil in any car I have looked at.

You need to clean out your system and keep it from getting full of leaves again. Some models are easier than others to get to. Often the blower motor can be pulled out or the blower motor resistor assembly can be removed from the plenum to gain access to the AC evaporator coil. With some cars these elements are easy to get to but others are very difficult. If you can get at the coil you can spray some detergent in there. I have also used 10% bleach after the detergents. If you use the latter I would not let it sit for more than a few minutes before rinsing extensively because you could corrode aluminum parts.

There are lots of cleaners and coatings for auto and home AC systems. Some Foaming or other cleaners rumored to be available for residential use should work. AirSept makes some coatings for Auto use. They require removal of the coil which will cost you time or money. I have not tried them.

Some car models seem prone to this problem. It must have something to do with how well the systems dry out after shut-off and how much crud collects in the “coil” (Now, I believe, many manufacturers use flat-plate heat exchangers.) I hope that the answer to the problem will be effective filters to keep the food away from the microbes that like to grow in moist, dark places.

I have spent a lot of time on this problem and I’ve had some generous help from people on web fora. Getting information about the auto manufacturers’ equipment was not easy. It seems that not many people out in the trenches (auto techs), even the factory-trained ones, know about them.

Despite the attempts at secrecy, I have found out how some of the manufacturers remedies work. Ford has a kit and a TSB (02-11-7 ,JUN 02, A/C System - Musty/Mildew Odors) . There is an “afterblow” or “purge” module and two wire kits to make it fit their various models. The price would be about $200 total depending on what wiring harness is needed. It runs the blower on high for a couple of minutes some time after the AC and car are shut off. The delay is important because no cold surface is going to dry with hot, moist air blowing over it. It also prevents operation at convenience store stops. I have also read recently that Ford no longer offers this stuff because of run-down battery problems. I don’t recall where I read this and I have not checked the facts.

Saturn has a kit for about $125 (delayed blower motor controller: 21031158). It seemed to be adaptable to any car. I was told that it runs the blower for 5 minutes after the car is turned off for 50 minutes to allow the coil to warm up.

Airsept probably still has a web site. They also make an afterblow module that is universal. The cost was about $300 to AC techs, I believe. It is costly, but it should work better than the others. Look a the site for the features. It starts a pulse cycle after giving some time for evap to warm. The pulse operation is supposed to squeeze the most out of your battery’s electrons by allowing the evap box warm up a little between the drying (cooling) pulses. It also has battery protection. It sounds good to me.

Airsept also makes cleaners and coatings to prevent microbe growth. These should also work. For most, however, you need to take the system apart to coat them. Note that there are foaming cleaners available for home HVAC. They should also work. Note that DSS (Dirty Socks Syndrome) is an issue with home units as well.

I think the problem might, in some cases, be solved with copper coils since copper would inhibit microbe growth. On the other hand, when all cars have cabin air filters the microbes will no longer have a food source for the microbes.

I live in a very hot/humid place. I pulled the blower motor from my car, cleaned and disinfected the evap. Fortunately one side is is readily accessible in my car. The evap looked sparkling clean, before I started so the microbe growth might be somewhere else in the plenum. I decided that I could make my own afterblow module with a little time and a soldering iron. I saved a lot of money and got great performance.

I went through several designs and decided that, in my climate, on most days when the humidity is high, I would need an auxiliary battery to dry the evaporator out with the HVAC blower in combination with systems like the commercial ones. I decided to reverse the afterblow. This blows cool, dry cabin air past the heater core and the evap. I made it with a small, plastic squirrel-cage blower, an inexpensive “multimode” timer kit and a couple of automotive relays. I plumbed the blower in to the passenger foot well heater outlet (not as easy as it sounds). I have a seasonal change-over of removing this and taking the duct tape off the other 3 heater outlets.

During AC season (10-12 month) I have to remember to put the system in the “floor” mode and turn the heater to high as I park. I have the timer triggered on the AC control so it activates if the AC has been on and runs the little blower for 2 h. I have a reset button and an on/off switch stuck behind the lighter in the ashtray. All the equipment is tucked up behind the dash. I have also added a little $20 pneumatic valve that opens the dash vent ducts when the blower stops to allow better circulation in case there is any residual moisture in there.

My solution is obviously not a universal solution, but it works for me and was inexpensive. My total costs were higher because I had a lot of false starts, but to repeat it would probably only cost about $30 excluding the valve. I did spend a lot of time on it.

The “Multimode Timer” kit is available at several mail/wwweb places. A couple:
http://www.oceancontrols.com.au/counters_timers/multi_mode_timer_k141.htm

Manual at: