TSB 24-11-97

A/C Evaporator Odor

Visit Geno's Garage for Truck accessories.

DATE  Jul 11, 1997

Models: CC lines (there are 21 distinct model lines) including 1994-1998 BR

Symptoms: A musty odor may be smelled especially at start up in hot and humid climates.  This may be the result of microbial growth on the evaporator core.  Condensation forms on the core and airborne stuff mixes with this and causes bacteria and fungi growth begins and odor results.  Just like your feet!

diagnosis: Operate the A/C system, if a musty odor is experienced, perform the repair procedure.

Parts:

1 ea. #04897625AA aerosol evaporator cleaner

Repair:  This repair involves inspecting for leaves or other foreign material in the evaporator and HVAC housing and applying Mopar aerosol evaporator cleaner.

NOTE: Follow all cautions and warnings supplied with the aerosol cleaner; keep out of reach of children; avoid contact with skin or eyes; wear protection; in case of contact, flush thoroughly; avoid breathing vapors. 

1. inspect the evaporator and HVAC housing for leaves or other foreign material that may be blocking air flow through the evaporator. If the build up is excessive, the evaporator may have to be replaced.
2. With the parking brake applied and the transmission in park, start the engine and let it idle. Put the temperature control to full hot, blower speed to high, select the PANEL and RE-CIRCULATE modes. Open all windows about 1/2" (13mm). Disable the A/C compressor clutch by disconnecting its wiring connector or the connector to the high pressure switch.
• NOTE: This procedure heats the evaporator and dries the moisture from it. The slightly open windows allow moister to escape while retaining enough heat to rapidly dry the evap. Run the heater for minimum 30 minutes. Sometimes a fog may cloud the windows - Run the heater until the "fog" on the inside windows has disappeared for 5 minutes.  In other words, dry out the evap coil well.
3. Switch the key OFF.
4. Get to the evap cavity to apply the cleaner by (in the BR/BE models) removing the blower resistor and covering the hole with a piece of masking tape and punch a SMALL hole in the tape to match the cleaner tube size.
5. The cleaner applicator tube has a black mark and a red mark in it.  The black mark is the mark for the BR/BE models. Insert only to the black mark!
6. Shake the can WELL, close the windows, start the engine and put the blower motor to high.
7. PUT ON GOGGLES AND DUST MASK BREATHING PROTECTION.
8. Spray the entire contents into the cavity.
• NOTE: A "fog" may be seen - it will NOT stain or harm the vehicle (so sez CC).  BUT GOGGLES AND BREATHING PROTECTION MUST BE WORN DURING THE CLEANER APPLICATION.  DO NOT BREATH VAPORS!
9. When the can is empty, turn the ignition switch off and let the vehicle sit for 20 minutes. This will allow the cleaner to flow over and coat the fins and case.
10. Replace the blower resistor.
11. Open the windows about 1/2 inch, start the engine and idle for a minimum of 30 minutes with the temp on full hot, blower high, panel and recirc modes selected.  This will dry and cure the cleaner onto the coil.
12. Reconnect the A/C wiring and verify correct operation.

RTML / DiRT Notes on the subject: 

Subject:  Re: DiRT: Smell in a.c.
Date:      Sat, 11 Jul 1998 07:31:31 EDT
From:     FOURWHL960@aol.com
 To:        DiRT

I had this problem in the past and the dealer sprayed something into the vents to make it smell better and that didn't work. They then replaced the condenser? and the problem reappeared. What did solve the problem was something I picked up on RTML a while back. Before you turn off your truck run the blower on FAN cycle for 5-10 seconds to clear out the cool damp air.

Dave

Subject:    DiRT: Smell in a.c.
Subject:    Re: DiRT: Smell in a.c.
Date:        Sat, 11 Jul 1998 10:33:58 -0400 (EDT)
From:       lance33@webtv.net (travis)
To:           DiRT
 
The mold in your a.c. builds up much like in your shower, causing it to smell. If you take it to a dealer, they spray a cleaner in the vents, and the smell will come back. You can prevent it from smelling. As you drive, the last couple of miles, run the fan only, no a.c. on. This will prevent it from smelling. (dries it out) To clean it, get a can of Lysol, start your truck, turn on the a.c. fan to high, outside air ,and spray about a half can of Lysol into the outside vent, under the hood, in the cowl area, this will kill the odor. The smell will come back in time, but just clean it again. Better then dealing with the dealer.

Subject:    Re: DiRT: Smell in a.c.
Date:        Sat, 11 Jul 1998 13:31:23 -0500
From:       RK <cteamco@linknet.net>
To:           DiRT

I don't have the old posts but I remember a highly touted solution that involved taking 18 to 24 inches of heater hose and clamping it onto the drain spout of the A.C. system and allowing the hose to hang past the frame. I don't remember the exact theory behind this other than allowing proper draining of condensation but it was reported that this remedy was successful on Rams along with many other makes of vehicles that are owned my Rammers.  I have only had one incident of the foul smell, which resembled dying/dead barnacles, so I never got around to implementing the remedy myself. I am only going on what was reported to the RTML.

Kevin Peden

Subject:    Re: DiRT: Smell in a.c./tubing
Date:        Sat, 11 Jul 1998 16:14:33 -0700 (PDT)
From:       "J. David" <avian1@yahoo.com>
To:           DiRT

---RK <cteamco@linknet.net> wrote:
> 18 to 24 inches of heater hose and clamping it onto the
> drain spout of the A.C. system and allowing the hose to hang past the
> frame.
 
 I took the hose advice and it seems to be working. I don't use the AC a lot, but wanted to head-off the problem that people were having from the older posts on the RTML.

 I bought 2 feet of 5/8 I.D. Tygon-type tubing at the hardware store. (I don't work for a research company anymore so I couldn't "appropriate" any!) It fits kind of snug over the condenser drain ,but I put a small hose clamp on just in case. I ran the tubing down and toward the back of the truck to where I could cable tie it to the frame.

 The theory, I think, was that the drain points to the front of the truck and the air coming up thru the engine compartment won't let the condenser drain smoothly. If you are not moving, you have no problem. I don't have any "musty" smell yet, but then I don't like to use Recirc. that much. It's like taking a bath in yesterdays bath water!

 JDE

Subject:    Re: DiRT: AC Stink
Date:        Sun, 12 Jul 1998 18:45:57 -0700
From:       Gary Newlin <gnewlin@surfari.net>
To:            DiRT

I wonder if trip length has a bearing on this problem?  I would imagine the "worst case" situation would be short trips in high humidity.

My daily commute is 40mi each way and after 18mos, no smell, defrost, or A/C, recirc or not.

And for what it's worth, I've always switched to a non-compressor mode a minute or so prior to arriving at my destination.  The intent here is to let the evaporator warm up a bit before engine shutdown.  This may minimize the condensation in the now stagnant plenum.

Sounds to me that extending the condensate drain into the slipstream may help.  Don't make it too long because if you get into a situation where the outside temp is below freezing, but humidity is high, it _could_ potentially freeze solid. (freezing fog)  I would hope that the exhaust manifold would supply enough heat to prevent this, but it's something to keep in the back of your mind.

Gary C.Newlin -- N6MZX

Subject:   DiRT: Musty AC smell
Date:       Mon, 13 Jul 1998 12:33:08 -0500
From:      David Clark <david.clark@analog.com>
To:          DiRT

I used to get this problem in my 95 RAM. Either I solved it, or it just went away by making sure I turned the AC off completely before shutting off the ignition. How this would have fixed it, I can't explain, but something made it stop.

--
 Dave Clark - Austin, Texas

Subject:    Re: DiRT: Musty AC smell
Date:        Mon, 13 Jul 1998 09:40:09 -0800
From:       David DeHaven <davidd@ixmicro.com>
To:           DiRT

> I had this problem in the past and the dealer sprayed something into the vents
> to make it smell better and that didn't work. They then replaced the
> condenser? and the problem reappeared. What did solve the problem was
> something I picked up on RTML a while back. Before you turn off your truck run
> the blower on FAN cycle for 5-10 seconds to clear out the cool damp air.

I've noticed running the A/C with the heat on (remember, it's air_conditioner_ not air cooler) a little bit will help too, since the heat will evaporate the moisture in the system.

David DeHaven