HVAC problem: Water on driver and passenger side foot areas

[jared999]

Initial issues: heat on driver side, cold air on passenger side. Water dripping on foot with AC on. Intermittent AC. No ac water draining underneath truck when AC is on.
Work done: I pulled the dash out, replaced all actuators except the vent actuator, replaced heater core, replaced evap core. Put everything back together. One of the old cores was very rusted on the bottom 3 inches.
Repair Result: AC blows cold on both sides but still have a lot of clear water (evaporated) coming into the foot area, both sides.

I stuck a coathanger through the drain tube and hit metal after about 3-4 inches. That seems too early to hit the bottom of the evap core.? Hmm... fyi the drain goes through the firewall and is under the dryer in the engine bay.

Is the water drained using gravity?

Why is the drain area cylindrical? Makes me wonder if something is in there that I missed that's maybe plugging it up (circled in red in photo)

 

[jared999]

hoping someone has done this job and can give me some pointers

 

[swathdiver]

hoping someone has done this job and can give me some pointers

Save for youtube videos, I do not recall too many doing this job on this forum. You'll have to search them out and then send a PM probably. I subb'd to learn but sorry to say nobody has chimed in.

@gpracer1 @91RS @Scottydoggs @Doubeleive @iamdub

Hey Fellas, who do you know that might know if you don't know?

 

[iamdub]

Initial issues: heat on driver side, cold air on passenger side. Water dripping on foot with AC on. No ac water underneath truck when AC is on.
Work done: I pulled the dash out, replaced all actuators except the vent actuator, replaced heater core, replaced evap core. Put everything back together. One of the old cores was very rusted on the bottom 3 inches.
Repair Result: AC blows cold on both sides but still have a lot of clear water (evaporated) coming into the foot area, both sides.

I didn't find anything plugging the drain pipe coming off the hvac lower case.

Is the water drained using gravity?

Why is the drain area cylindrical? Makes me wonder if something is in there that I missed (circled in red in photo)

I'm with @swathdiver. I don't recall many going this far into these things. It's usually actuator replacement and/or programming on the GMT800 models.

I know the system has a drain that empties outside, behind the passenger side wheel. With no water underneath, I'd say this outlet is clogged. Maybe a dirt dauber nest? Does that part you circled pass through the firewall and connect to a short hose?

 

[Scottydoggs]

at the end caps of the wind shield cowl theres caps that lift up. dirt gets all clogged up under the cowl and can cause a leak at your feet on the pass side. i had a o5 work truck do this, i just hosed it out form both sides, never leaked again. there was also dirt and mud right inside them caps, was pulling it out with my fingers. said cap, pass side. https://photos.app.goo.gl/qPYhAfZ7mSpomsCL6

 

[91RS]

The AC drain is gravity but the elbow acts as a siphon when driving down the road. I’ve seen a handful get clogged and I’ve always been able to unclog them from the outside.

 

[jared999]

The AC drain is gravity but the elbow acts as a siphon when driving down the road. I’ve seen a handful get clogged and I’ve always been able to unclog them from the outside.

Got it, thanks. One of the first things I did was pull off the rubber boot and put a thick zip tie in that drain tube, and a coat hanger. I didn't hit anything except metal. I can't say I hit the evap core because it didn't go in all that far. So I was hoping if someone knew more about the cylindrical shape and if it contained something in there to prevent back flow

 

[jared999]

Thank you your the suggestions and ideas.

I'm going to do some thinking on this before I tear it all back out. If there is no back flow valve in that drain tube, then I'm hitting something in that drain tube that shouldn't be there.

 

[jared999]

I decided to stick a video scope in that drain tube and I found what my coat hanger was hitting. Rusted crap. So clearly, I wasn't getting in far enough to hit the bottom of the evap core. That makes sense because it didn't feel like it was going in far.

It doesn't look like enough debris / rust to block water, but I'm going to try to drill that out with a 5/16 bit. From there maybe use a long pipe brush / metal brush to try to clean the tube out. Perhaps that will be enough and I won't have to pull the dash again. I'm not optimistic, though.

 

[jared999]

I drilled that out with a 5/16 8" long bit and as soon as I did water started to pour out. Once the water stopped I took a long brass pipe cleaner and ran it in until it didn't hang up any more. Hopefully that evap core isn't shot because its been sitting in water for a while now...

 

[iamdub]

I drilled that out with a 5/16 8" long bit and as soon as I did water started to pour out. Once the water stopped I took a long brass pipe cleaner and ran it in until it didn't hang up any more. Hopefully that evap core isn't shot because its been sitting in water for a while now...

I'm gonna check mine out!

 

[jared999]

I'm gonna check mine out!

Are you getting water at your feet?

 

[iamdub]

Are you getting water at your feet?

No, but I don't wanna wait 'til mine gets to the point yours did

 

[jared999]

No, but I don't wanna wait 'til mine gets to the point yours did

Gotcha. Well, when I look at those video scope photos, that looks like rust build up. Maybe some smaller metal fragments from the evap core made there way in there and got stuck, who knows. You can get a 12" pipe brush and run it in there. A 5/16" is a snug fit, but it works well. I used brass so it wouldn't damage the tube.

 

[Trixxterr]

Thanks for the info. When I got home from work this morning, I had to get something from the passenger side.. when I opened the door I noticed the floor was wet! Just the floor, not the firewall part where you rest your feet. So I came looking for advice and info. Thanks for posting, I have a direction to go, and something to look into..

 

[ClaytonFLong]

at the end caps of the wind shield cowl theres caps that lift up. dirt gets all clogged up under the cowl and can cause a leak at your feet on the pass side. i had a o5 work truck do this, i just hosed it out form both sides, never leaked again. there was also dirt and mud right inside them caps, was pulling it out with my fingers. said cap, pass side. https://photos.app.goo.gl/qPYhAfZ7mSpomsCL6

Where is your picture pointing at? Location?

 

[Scottydoggs]

Where is your picture pointing at? Location?

right next to the hood hinge.

 

[89Suburban]

Very interesting! Putting this on my tinkering list!