My AC smells like mold when I first turn it on. Is there a plugged drain hose or something I can do to clean it?

 

an old post that might be of help:
====
>One of you posted the following article....

>>Chrysler revised its procedure for dealing with
>>musty a/c for all cars and trucks up to 1998. Order up Part No. 04897625AA
>>Aerosol Evaporator Cleaner.

>My dealer wanted 46.25 + tax. Have any of you tried this to see if it works?

Alex, I posted that from 'Service Slants' at Motor magazine.

I haven't tried PN 04897625AA,
but I did read about another method for Rams in one of the posts at
alt.autos.dodge.trucks.

A guy who said he was a professional microbiologist said that he got rid of
the odor from fungus that grew on the AC evaporator by attaching a hose to the
AC drain and pouring in a quart of ethyl alcohol {"rubbing alcohol"} and let
it set overnight. The poster said the vapor from the alcohol also sterilized
the ducts and evaporator pan. He claimed alcohol wouldn't hurt the metals
inside.

I knew that 'Lysol' is 98% ethyl alcohol, 1% perfume and 1% phenol, so this
sounded correct. Many people have used Lysol to get rid of AC odor, but some
don't like the Lysol smell.

I was interested in this method because I already had a hose set up to go on
my Ram's AC drain tube { from my water injection experiment into the PCV for
pinging}

1. I parked my Ram on a level spot.
2. I placed a towel underneath the AC housing on the passenger side interior
of the Ram to catch any possible alcohol spill. The original poster advised
this.
3. I attached one end of a half inch internal diameter clear plastic hose
about 30 inches long to my AC drain on the passenger side rear of the engine
compartment. You have to slightly enlarge the hose end to get it to go onto
the AC drain tube.
4. I put a funnel on the other end of the 1/2 inch hose.
5. I didn't have any ethyl alcohol so I used isopropyl alcohol I had in the
bathroom cabinet. { I also seem to remember that methyl alcohol will attack
aluminum, and ethyl rubbing alcohol has some methyl alcohol mixed into it to
'poison it' so people won't drink it.}
6. I poured a quart into the hose and let it drain into the AC evaporator. I
tied the other end of the hose off up high so the alcohol couldn't drain back
out.
7. No alcohol spilled out in the Ram's interior onto the safety towel from one
quart's worth.
8. I closed the adjustable vents on the Ram's dashboard with the thumbwheels,
and covered the vents at the base of the windshield with magazines -like the
poster suggested.
9. I left the alcohol to sterilize things overnight.
10. In the morning I lowered the end of the 1/2 inch hose into a container and
drained out the alcohol. The alcohol was perfectly clear when it was put in -
but it came out "pea green" color.
11. There was a strong odor of alcohol in the cab of the truck so I opened the
doors and let it air out for an hour before I started the fan - I was slightly
worried the alcohol fumes might explode from electrical sparks if the fan was
turned on too quick - a coal miner's caution.
12. When I started up the truck I drove around with the windows down at first.
I wondered what I would tell a cop about the odor of alcohol if I got stopped.

13. About 3-4 days later I noticed that some fine grey colored dust had
accumulated around the vents beneath the windshield. I guessed that this dust
was dead and dried out fungus and vacuumed it away. I was slightly worried
that the grey dust might be aluminum oxide powder, which would indicate the
alcohol had attacked the aluminum tubes of the evaporator.

This was about a month ago and the smell from the AC vents when the fan is
first turned on has not come back yet.

I had been waiting to post this because I wanted to see how long it would take
for the fungus to grow back.

This seemed to work good and is very cheap since the alcohol costs about $1.25
per quart - but it might be safer to use the PN 04897625AA since {I hope}
Chrysler designed this stuff to not attack anything in the AC evaporator.

 

Thanks Hank. I thought about bleach, but didn't even think that it might corrode the fins.

 

here's an alternative low-tech approach. buy a can of lysol "crisp linen scent". turn on defroster and fan on low and spray a heaping helping of lysol into the passenger side cowlbeside the windshield wiper. you will see it getting sucked in. spray for about 30-60 sec.