Hello,

I have an 04 monte carlo that drips water down the plastic housing on the heater core on to the passenger floor.

I replaced the heater core initially, but soon after still saw the drip.

When I takeoff or stop/go I can hear what sounds like water rushing around behind the passenger dash. The liquid doesn't smell like coolant either.

I have checked the cabin filter to see if maybe the water was coming in from the hood cowel, but it was dry.

I also removed the AC drain plug from the firewall, the elbow was dry and the fitting it was on was also dry.

Any insight on what to try next would be great, I'm stumped at this point.

 

Only time I hear water moving is when the drain holes on the door get clogged due to failed weatherstripping.

Not sure how that would make its way to the floorboard tho.

 

I would say your evaporator condensation drain is plugged up. You said the drain elbow was dry - are you seeing condensation on the ground under it when you hear sloshing? Try sticking a piece of wire up into the elbow as far as it will go a couple of times. Dust & bugs can get up in there and a little moisture mix will create a blockage.

I'm assuming you don't have a sunroof like fatalcMCSS does. And that you have confirmed the door is draining properly. If it was from a plugged up door, you probably wouldn't see it except from below the speaker grill.

 

Check the seal around your cabin air filter , that's usually one of the culprits. I have also ran into simular situation where after a friend changed heater cores he had some simular problems. Solution was a new box for heater core it had too many cracks and water wouldn't make it to the drain . Good luck.

 

Also, for those who didn't make it to the tech guides or know to look. I actually scored one for no charge in my seat haul. The part is listed as still available.

https://montecarloforum.com/forum/fw...lem-fix-26663/

 

I see condensation on the ground after i get out of the car after running A/C.

I already tried sticking a metal coat hanger into the plug the drain elbow sits on. Nothing seemed blocked.
My door drains are clear.
And the cabin filter was dry, also about the cracked heater core box. It leaked before even when the heater core box had never been touched. I replaced the heater core and put all the original plastic back.
However, I do have a sunroof.

 

If you have a sunroof, have you blown out the drains with compressed air?

 

I have not, would those cause water to sound like its stuck swirling behind my passenger dash and water to drip off heater box plastic on top left of passenger floor only when the A/C is on?

 

Ahh didn't realize it was only when the AC is on.

But yeah the sunroof drains do run down the A-pillar and could cause water inside the car.

 

yea, check the bottom door seals, mine did that were clogged up with dirt and debris, wipe under the rubber seal real good and poke a wire like a coat hanger in the drain holes? hope this helps