Allpar is only 1/2 correct.
P/N#: 4897625AA (Evaporator Cleaner/Disinfectant) is what is used by
TSB#21-11-97 (Requires either drilling a hole into the evaporator case,
removing the blower motor resistor, or removing the blower motor to gain
access directly to the evaporator).
"Some vehicle operators may experience a musty odor from the A/C system,
primarily at start up in hot and humid climates. This odor may be the result
of microbial growth on the evaporator core. During normal A/C system
operation, condensation forms in and around the A/C evaporator. When
airborne pollutants mix with this condensation, bacteria and fungi growth
begins and odor results."
The odor is definitely caused by mold/mildew on the evaporator (and only a
small portion is on the foam pad that it resides on). I've yanked way too
many stinky evaporators and can tell you from experience that the smell
doesn’t come from the vents. Putting baking soda/water into the drain hole
will only get a very small portion of the evaporator and you risk soaking
the foam pad to the point of it plugging up the drain hole (seen that happen
as well).
Drying out the evaporator (as stated in AllPar) is one of the last steps in
the TSB:
"Open all of the vehicle windows about 13mm (½ in.). Start the engine and
let idle for a MINIMUM of 30 minutes with the temperature control to full
hot, blower speed to HIGH, PANEL and RE-CIRCULATE modes selected. This will
dry and cure the evaporator cleaner onto the evaporator coil. "
Again....unless you can get access to the evaporator, spraying anything into
the vents (in the cab) is useless. The ducting is fairly long and not even
close to being a direct path to the evaporator. Plus, the mold/mildew forms
on the blower-motor side of the evaporator...not the ducting/vent side. The
Wynns "Fresh Air" aerosol is also a vent treatment...not an evaporator
cleaner.
Here's a good picture of what most evaporators look like at about 50-60K
miles (and I've seen worse in vehicles where people smoke with the windows
closed and/or A/C on recirc):
http://www.bgfindashop.com/unitedstates/includes/cc_serv.php
BG P/N# 709 is what you can use...and can pick up at most Hi-Lo/O'Reily's or
NAPA. It's a true evaporator cleaner kit (approximately $30 retail).
Follow it up with the BG "Frigi-Fresh" P/N# 708 if you want...makes it smell
"fresh".
- Bernd
-----Original Message-----
From: owner-dakota-truck@bent.twistedbits.net
[mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of Bob Tom
Sent: Sunday, May 29, 2005 7:03 AM
To: dakota-truck@dakota-truck.net
Subject: RE: DML: Air Vents & Funky Smells
At 08:58 PM 5/28/05, you wrote:
>As long as you can get it to the evaporator - that's where 99% of the
>smells come from. Spraying stuff into the vents is rather useless. -
>Bernd
Treats all components of the HVAC system.
http://www.wynns.ca/data/msds/english/wynns/15003.pdf
The Allpar site has some added info. and suggestions that appear opposite to
yours at:
http://www.allpar.com/fix/acsmell.html
Bob
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