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Bad odor from AC vents

08-05-2003, 08:46 AM
Just recently my wifes 1999 Grand Cherokee is spewing a foul odor when the AC/Heat or defroster is turned on. The Vehicle is spottless, non-smoker, AND only 40k miles. My guess was that something is in the cowl area creating the smell (pollen, dirt, leaves). I tried to flush it out and used the orange cleaner but It didn't help. Where is the air drawn from before entering the vehicle? Or could this be something else.

It is not antifreeze, freon or exhaust. It like a musty damp basement/locker room BO smell


09-17-2003, 09:04 PM
I have the same problem and I cleaned the vents, too. I will be looking into it soon, there must be some AC/vent filters that collect debris.

10-03-2003, 06:14 PM
I have had the same trouble with my old 94. My 2000 model has not had it but I'm sure it'll happen. The "stink" was mildew and mold that builds up inside the moist environment when the AC is on. There are products at any auto store which are aerosol vent cleaners. Spray it into the air intake (below wipers on the pass side) and it kills all the nasties. I have heard that some of the cheaper products can erode the evaporator core in some cars so get a quality product and follw the directions.
The prevention is to turn on the heat once and awhile to warm up the air ducts (I do it once a week for 2 mins at a time and blast to the floor).
Good luck :eek7:

10-05-2003, 01:01 AM
the smell is mold growing in your ac/heat ducts. what happens is when you have the ac on the evaporator removes moisture from the air before it enters your vehice, and the water drains outside, that is when you are parked after you have had the ac on your jeep will drip water. that drain is plugged witch wont allow the water to exit your vehicle and it is just sitting in your ducts growing mold. you will have to open up the ducts, not sue where n your vehicle, and blow out that drain,

DIY Mechanic
10-24-2003, 08:35 AM
The dealer has a fix for this.
Part Number 4897625AB

Or you can go down to your local Heating & Air Conditioning Supply house and purchase ‘Evaporator Cleaner', for about $10/gallon and it is diluted 3:1.

The procedure for both is to;

Run the vehicle with the heat on max, fan on High for 5-10 minutes.
This is to remove the moisture from the inside air supply box.

Next remove the access panel next to the fan motor.
Turn the fan back on to High and spray the evaporator.
The engine may or may not be running for the application.

The Mopar spray can has a very long nozzle like the short one that comes on a can of WD40.
The Supply House cleaner will need to be applied with a sprayer, like a pump up garden sprayer.

The Mopar spray will not harm the interior of the vehicle but the Supply House liquid must be watched. It to will not harm Leather or Cloth but I do not recommend spraying until a mist is coming out of the vents and it my drip from the panel opening you are spraying into.

Have towels ready to catch any liquid that may run out.
The Mopar spray is a vapor and will not run out onto the carpet.
Both are not harmful to you or the environment.

11-09-2003, 09:15 AM
cleaner is like a band-aid, you'll need to change the evaporater and pay attention to the cowl area, remove any leaves whenever you see them, they have acid and destroy the car's evap. i have changed dozens of them literally. it is a big job. i do them for 600 parts & labor.

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