defroster smell

2000 Explorer
I have a moldy smell when I first turn on my defrosters in the morning. I bought a spray that is supposed to kill the mold. It says to spray it in to
the fresh air intake> Can anybody tell me where that is?
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Ralph J. wrote:

Between the hood and the windshield.
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Gordon S. Hlavenka http://www.crashelectronics.com
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The fresh air intake comes through the grates that are in front of the windshield below the wipers.
I have a 1997 Explorer that developed a moldy smell when the defrosters or AC was turned on too but went away after about a minute or two of running the blower. It tried the sprays and the deodorizers and they worked for a while but the smell kept coming back so I decided that I had to get to the root of the problem.
I originally thought that the drain line from the enclosure that surrounds the AC/defroster condenser coil was clogged resulting in standing water and causing the foul smell. I ran the AC and watched to see if there was condenser water dripping out from below the vehicle. I did see some water dripping out, which also helped me locate the drain line, and figured that maybe it was only partially clogged. So I pushed a stiff wire into the drain hose to see if there might be a partial obstruction. A little debris came out so I assumed that I had fixed the problem, but the problem returned again even though I was getting adequate drainage.
I then concluded that a more thorough cleaning would be needed to get rid of this smell. The easiest way that I could see to gain access to the AC condenser coil without a major disassembly of the vehicle was to remove the blower motor assembly. On a '97 it's pretty accessible being under the hood on the passenger side right up against the firewall. I had to remove a couple of screws from the washer fluid and coolant reservoirs and move them forward slightly to get the blower motor with it's attached flange out. Once that was out I could see the condenser pretty well. I found that my problem was caused by debris (leaf particles and other small organic particulate) that had accumulated at the bottom of the enclosure that houses the condenser coil. Since this junk was damp, mold had begun to grow and cause the odor.
Unfortunately, the parking lot where I work has a row of large shrubbery right in front of the vehicles. Every time the wind blows, debris from these shrubs gets blown onto the cars. While most of it is large enough to be blocked by the grating, some of the smaller particles managed to get through. After a few years of this, enough junk got down into the condenser coil area and started to decay causing the odor. The problem seemed to be worse in the summer especially since my truck is kept in the garage. The combination of dead leaves and debris, condenser water and heat made things pretty stinky.
I was able to clean out the debris by sticking a garden hose into the blower motor opening and flushing all the gunk out. If you try this make sure you get both sides of the condenser coil. I was able to get the spray from the hose to the backside of the condenser and wash it out too. I then let the water drain out from the area and sprayed it with a water/bleach solution to kill all the mold. I haven't had the odor since although I suspect that another cleaning in the future will be necessary as the same thing will probably occur after a few more years of accumulating junk from the shrubs.
Good luck and I hope this gives you a little insight to solving your problem.
Don
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Check the NHTSA website (or wherever...) Seems to me there was a TSB about this....

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Seems like there is a "perpetual" TSB for this. If it's the one I'm thinking about, it seems to get issued for just about every year, and consists of some type of chemical/spray that is introduced into the evaporator compartment of the AC system. Seems like it was more than just a deodorizer - I seem to remember the TSB mentioning some type of "encapsulation" spray with a specific methodology for application. I had the dealer do this to mine while it was still under warranty, and it really did help for about two years, after which the smell came back. Sounds like Don R. diagnosed the real root of the problem. I don't seem to have as much trouble if I spend most of the summer using Max A/C... my guess is that maybe this keeps recirculation damper open even while parked, giving the evaporator compartment a better chance to dry out...
Steve

I
in
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Just_Steve wrote:

The problem I have is not a moldy smell, rather a smoky smell. Sometimes so intense I have to crack a window to get some fresh air so my eyes stop burning! The reason is that in my '94 the leaves and crap get into the plenum and pack up against the power resistors for the heater blower motor. Whichever resistor is selected for a given blower speed will get hot -- some of them VERY hot -- while the blower is on. I've found that running the fan on high is least likely to make the burning smell (aside from "off" :-), whether because that position uses no resistor, that resistor doesn't get as hot, or that resistor is located so that crap doesn't pack up against it.
A couple of times I've taken apart the blower assembly and pulled out the junk, but it's a real PITA to get at.
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Gordon, My '94 EB had the leaf problem so bad that one night they caught fire. You haven't lived until you're driving down a foggy road at midnight, turn on the fan and start seeing smoke billowing out of the vents. I kept thinking that there "must be a forrest fire around here somewhere". I luckily turned off the fan so that I wouldn't "fan" the flames but it smoldered for quite a while.
dave

much
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Thanks to all
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