Funky smell from AC

[jwakil]

I have a moldy smell coming from my AC vents on my 930. I notice it when AC is on and seems to get stronger when I accelerate, but that could be my imagination. I have an upgrade kit from Retro Air, but I didn't install it myself. I was going to start by checking/cleaning the evaporator and drain. What's the easiest way to do this? I want to do what doesn't involve disconnecting AC hoses first.

[Cajundaddy]

Sounds like clogged condensate drains. Often just running a wire through the drain tubing is enough to clear it.

[DRACO A5OG]

+1

Maybe running some water over evap will help too

[Rawknees'Turbo]

If you remove the passenger's floorboard, you'll see the plastic intake duct for the evaporator box (the fan speed resistor pack is attached to it) - unplug the resistor pack and remove the intake duct (it actually sticks into the evaporator box a little bit), and then you will be able to somewhat see the bottom of the box (where the drain is that those guys mentioned above) and the bottom side of the evaporator core (a flashlight and mechanic's mirror helps a lot). You can check for mold buildup and then clean accordingly, that way.

[86 911 Targa]

Originally Posted by Rawknees'Turbo

If you remove the passenger's floorboard, you'll see the plastic intake duct for the evaporator box (the fan speed resistor pack is attached to it) - unplug the resistor pack and remove the intake duct (it actually sticks into the evaporator box a little bit), and then you will be able to somewhat see the bottom of the box (where the drain is that those guys mentioned above) and the bottom side of the evaporator core (a flashlight and mechanic's mirror helps a lot). You can check for mold buildup and then clean accordingly, that way.

^^^^^
Correct.

Also, as I have done, use a non-metal soft rod (plastic) to clean out the drain tube from underneath the car while using a water spray to clean the bottom of the evaporator housing where in most cases the crud will be.

Maybe someone will also suggest a disinfectant.

Best,

Gerry

[Oyagi]

Great advice, and here I am driving with the smell thinking it's just "old car smell"


Sent from my iPad using Tapatalk

[steely]

I think you can use a TSP of bleach in a gallon of water, or white vinegar but don't know the ratio offhand

[kuehl]

You can check the evap box drain tube from under the car, RH side under the car, adjacent to the splash pan covering the cross member, the drain tube is plastic, part of the lower case of the evaporator box. You can use a small wire and insert it up no more than 3" would be safe so you don't damage the evaporator up above. In some cases the molded plastic evap drain tube may not be visible, in cases where it has been broken off.

Follow Rawknee's suggestion to remove the carpets on the RH passenger, remove the wooden floor board, remove the black plastic trapezoid shaped RH side air intake plenum (4 screws hold it in, leave the evap motor fan speed resistor pack inside it, just unplug its wire if necessary). Take a flashlight with a mirror and look up inside and you see the bottom of evaporator in the box. Do NOT use any wires or tools to try to clean it else you will bend the cooling fins and could puncture one of the evaporator tubes.

If you do not see a lot of mold or crud, say something that looks like THIS on the evaporator there are disinfectant evaporator aerosols designed for eliminating mold and smells. You could spray this inside the RH intake plenum area into the coil and see if it helps (provided you don't have a lot of crud; it will not remove heavy deposits). The air flow through the evaporator is from south to north, hence you could turn on your ign key to 'accessory' and turn on the evap fan blower (windows and doors open, and wear a respirator; don't breath in the stuff).

If the evap has a lot of crud, you could 'carefully' remove the evap box top, leave the refrigerant lines connected to the evap outlet and expansion valve inlet, and lift and tilt the evap out of the box, carefully, toward the driver's side; you won't have much wiggle room.

If you want to read up "more" on what a dirty clogged evaporator coil can do to the system and you, here is a some good threads to read:

The Short Version
and the Long Version

[jwakil]

Well, I removed the floorboard and checked the evaporator and drain. They both looked pretty good. There was no big buildup of mold or standing water there. Also, it didn't smell very bad there. Where it smelled bad was the vents on the dash. So I thought maybe my windshield was leaking from my last install. I removed the windshield, and also saw nothing unusual. Even if it did leak I don't know how the water would go into the vents. Anyway, now I think I have some mold or something growing in the vents and duct work, so I will try the sprays and mold killers I've heard of. Not in any mood to take everything apart. Any suggestions on products and methods to do the spraying?

[kuehl]

If the HVAC ventilation is stock, the side vents also provide heated air. Air coming from the engine, exhaust heat exchangers, etc. can have various smells; gas, oil, rust, metal, and so on.
HVAC Controls

Check if the smell lingers when you
a) close off the vents,
b) push down the 2 heater box valve levers to the floor,
and go under the car and check if the heat box valve flaps are closed all the way
Reference pic

[jwakil]

It's definitely not any engine smell. I know those smells: burned oil or smokey. This is moldy rotten, and I can actually smell it when the car is off if I stick my nose close enough to the vent.

[kuehl]

Pull up the RH side front carpet.
Remove the wooden floor board.
Remove the black plastic trapezoid shaped RH evap box plenum.
Get yourself a can of Lysol.
Get your self a fire rescue Scott air pack or see how long you can hold your breath.
Turn on the ign key to accessory on, turn thermostat to max cold, turn
evap blower to max speed, open all the windows and doors, soak the bottom of the evap coil.

Other sources of 'smell' when AC is on could be mouse that crawled up in the smugglers box or the heat box flap.
Mildew in the center 'tunnel' (runs under the center console to the rear; shift rod boot is broken
allowing outside air to collect in tunnel).

Find the source of the smell is not as hard as geocaching.