Leak under passenger side

[scott_williams2]

I have a 97 k1500 and recently I noticed a leak under my passenger floor board. I traced it for a fact to the AC evap. I don’t have any ac performance complaints but it’s cuttrntly ruining my carpet and causing it to stink. I did research and changing the evap seems to be a major PITA. I thought maybe it was clogged but it drains good. Any help would be appreciated

 

[east302]

Did you ever pinpoint exactly where it’s leaking from? Maybe rub some chalk or some kind of powder all over it to help spot the source.

The case is split and comes from the factory with a thin RTV between the halves - starting roughly at the heater core and going back to the portion containing the evaporator core. You can see a piece of it hanging off in the photo at the heater blend door...

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At a glance, it would have to be really flooded to spill through those seams.

Pulling the dash takes an hour or two, the rest is straightforward. You might be able to open the case without pulling it from the firewall but I’ve never tried it that way.

 

[Schurkey]

I have a 97 k1500 and recently I noticed a leak under my passenger floor board. I traced it for a fact to the AC evap. I don’t have any ac performance complaints but it’s cuttrntly ruining my carpet and causing it to stink. I did research and changing the evap seems to be a major PITA. I thought maybe it was clogged but it drains good. Any help would be appreciated

I don't understand how it can "drain good" but have enough trapped water to dump onto your carpet. Is the evaporator box cracked/broken?

My Monte Carlo had a plugged evaporator drain duckbill. The water was so deep in the AC box that when I went around left-hand turns, it would slosh into the HVAC fan, make noise and mist would come out of the dash vents. The water corroded the HVAC resistor pack so the fan eventually quit working. I couldn't even unplug the resistor pack from the wire harness, the connector had corroded to the resistor pack so bad it wouldn't come apart.

I pulled the duckbill off, and got over a quart of water spilling out of the drain tube. Got more when I lowered the jack that was holding the front of the car up so I could crawl underneath. Installed a resistor and a 4-wire connector with a few inches of wiring, spliced it into the existing harness, and all is good now.

 

[scott_williams2]

I don't understand how it can "drain good" but have enough trapped water to dump onto your carpet. Is the evaporator box cracked/broken?

My Monte Carlo had a plugged evaporator drain duckbill. The water was so deep in the AC box that when I went around left-hand turns, it would slosh into the HVAC fan, make noise and mist would come out of the dash vents. The water corroded the HVAC resistor pack so the fan eventually quit working. I couldn't even unplug the resistor pack from the wire harness, the connector had corroded to the resistor pack so bad it wouldn't come apart.

I pulled the duckbill off, and got over a quart of water spilling out of the drain tube. Got more when I lowered the jack that was holding the front of the car up so I could crawl underneath. Installed a resistor and a 4-wire connector with a few inches of wiring, spliced it into the existing harness, and all is good now.

It drains good but I can run the ac and watch water drop off the bottom of the evap like condensation or maybe little holes idk how to better explain it. Like I said I have no ac problems I just wanna save my carpet

 

[Schurkey]

Photos?

 

[df2x4]

Are you sure the drain line isn't partially clogged? Just because it's draining doesn't necessarily mean it isn't obstructed. You could be generating condensation inside the box faster than it can drain out.

 

[Donald Mitchell]

did you clean out the drain under the hood? If it cant run out it will run in.

 

[scott_williams2]

How and where can I see if it’s partially clogged? Compressed air?

 

[Donald Mitchell]

I would use a long skinny screwdriver and see what you can get out, then there are other options but blowing the crap back into the evaporator isn't one of em.

 

[east302]

The drain nozzle is maybe an inch long, just enough to connect to the case and go through the firewall. Swirling a screwdriver around should suffice along with using a mirror to check the bottom inside of the case through the blower opening. The core fins bend very easily, so don’t go animal on it.

If you can, use a mirror and flashlight to see if you can spot any leak source on the side of the case that faces the firewall.