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How To - Unclog Your A/C Evaporator Drain Tube


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#1 Fireman31

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Posted 05 July 2010 - 08:36 PM

If your truck isn't a Daily Driver and sits alot, you may encounter this problem. Recently, I had a flood in my SSS. Driver's Side and Passenger Side floor boards front to rear were soaked with water after a 5 hour road trip with the A/C on. No, it didn't rain at all. Upon checking the A/C Evaporator Drain Tube, I noticed it was dry. After sucking the water out of the rug with a shop vac, here is what you need to do to clear the clogged tube.....


TOOLS NEEDED -
pipe cleaners, found at any craft store or smoke shop
wet/dry vac
Febreze


Step 1 : Locate the drain tube(Passenger Side firewall under AC Accumulator).
Attached File  HPIM1489.JPG   1.32MB   517 downloads

Step 2 : Remove the drain tube from the AC Evaporator outlet(Grab and twist/pull).

Step 3 : Use a pipe cleaner and clean out the drain tube.
Attached File  HPIM1483.JPG   1.29MB   435 downloads

Step 4 : Use a pipe cleaner and clean out the AC Evaporator drain outlet, you may see the obstruction, but be careful not to knock it into the Evaporator.....You will get a nice gush of water as the Evaporator drains out. Please note that it may also drain back into the cab of your truck too, so have your shop vac ready.
Attached File  HPIM1485-2.JPG   524.15KB   258 downloads
Attached File  HPIM1484.JPG   1.32MB   344 downloads

Step 5 : Re-install the drain tube and run your truck's A/C to make sure the drain is working properly.

This is what came out if mine, it was right at the opening to the Evaporator.....
Attached File  HPIM1488.JPG   1.31MB   358 downloads
....a spider's nest full of eggs! :freak:

NOTE -
Do not use compressed air, not only can you blow the obstruction into the Evaporator, if it is really stuck(like mine was), compressed air won't even do anything to remedy the clog.
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#2 Fireman31

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    The choppy idle is just a bad misfire, I swear!!!

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Posted 05 July 2010 - 08:46 PM

Forgot to mention, failing to correct this issue will result in a moldy smell in your truck, puddles on your floor, and worse yet.......a blown blower motor and resistor. :uhoh:
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#3 WODY™

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Posted 05 July 2010 - 09:41 PM

good info danjamin!

there is an a/c coil cleaner that i'm sure is available at any major automotive store. that stuff works wonders. clean out the drain tube and just pinch them on occation to make sure they are clear. every-now-and-then, its also a good idea to run the fresh air for a while and not only recirculation, this will help cure that raunchy mold smell. with that much restriction around your evaporator, you were probably getting some ice build up.

on the freightliner M2 business class trucks, the a/c system will actually shut off if the filter is plugged up, but that doesn't always prevent the blower motor from overheating and burning the wires.

if you live in a humid envorinment and see the condensation from the evaporator dripping on the outside of the truck, then its pretty safe to say that your drain tube is clean, but if not...you may want to check them.

unfortunately, if you live a dry environment, like vegas, you won't always see water dripping, so it is a good habit to get in at every oil change just to squeeze the drain tube.

Edited by WODY™, 05 July 2010 - 09:45 PM.

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#4 ynot333

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Posted 22 July 2010 - 10:31 PM

good info danjamin!

there is an a/c coil cleaner that i'm sure is available at any major automotive store. that stuff works wonders. clean out the drain tube and just pinch them on occation to make sure they are clear. every-now-and-then, its also a good idea to run the fresh air for a while and not only recirculation, this will help cure that raunchy mold smell. with that much restriction around your evaporator, you were probably getting some ice build up.

on the freightliner M2 business class trucks, the a/c system will actually shut off if the filter is plugged up, but that doesn't always prevent the blower motor from overheating and burning the wires.

if you live in a humid envorinment and see the condensation from the evaporator dripping on the outside of the truck, then its pretty safe to say that your drain tube is clean, but if not...you may want to check them.

unfortunately, if you live a dry environment, like vegas, you won't always see water dripping, so it is a good habit to get in at every oil change just to squeeze the drain tube.


evap-foam for the indoor and nubrite for the out door one..............
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#5 1slow03

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Posted 12 August 2010 - 03:25 AM

Nice my tuck is doing this and i was wondering how to fix it thanks for the info.
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#6 JroCk817

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Posted 09 March 2012 - 02:26 PM

GLAD I FOUND THIS!!! I was having the same problem...
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#7 Fireman31

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    The choppy idle is just a bad misfire, I swear!!!

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Posted 09 March 2012 - 07:00 PM

:thumbs:
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