Whenever it rains, water leaks out from somewhere under the glovebox near the firewall, soaking the carpet a bunch

It's been mentioned that it might be a clogged hvac:
Not really sure how to start attacking this to remove the hvac stuff though.. just start unbolting whatever I see under there? lol

 

DO you have a sunroof?
there are drain tubes too that come down the front and back sides that could also be clogged.

 

I had a GXL that did this when the AC was turned on, passenger footwell would turn into a small lake. The FSM is available online, I'd use that as a reference.

 

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I believe the front sunroof drain hoses go down the A Pillars

 

If it's happening only when it rains or you wash the car, it's most likely the sunroof drain. There is a hose at both front corners of the sunroof assembly that run through the A-pillars and exit underneath the car. If they are clogged with debris, disconnected somewhere, or if the sunroof assembly is rusted out, water will find its way down there.

Now if you're finding water down there ONLY when the A/C is running, it's a clogged or broken A/C condensate drain for the evaporator core. On the lower part of the passenger side firewall, under the hood, you should see a short aluminum tube sticking out with an open end that bends down at a 90* angle towards the ground. That's the drain tube, and it connects to a rubber hose/tube connection in the evaporator core case. Use something like a wire or pipe cleaner to check that the tube is clear of debris. If it was blocked, when you unclog it, all the backed up water will flow out. If it wasn't blocked, then the tube may have become disconnected from the evap core case, or the case itself may be cracked, so water leaks out that way instead of flowing out thru the tube.

 

Check your windshield too. I could be a bad bond between glass/body due to windshield adhesive debonding.

 

Thanks everyone - I do have a sunroof, so I'll take a look at what's been mentioned. The leak happens independent from AC (since mine doesn't seem to work anyway) or any HVAC usage actually.

One weird thing or clue though: I thought that the water sitting in the passenger footwell was all of it, so I soaked it up with some towels and dried it the best I could. When I started to move the car though, a bunch of water dumped out directly from where I think the HVAC unit is, and onto my passenger's left foot lol. Not sure if this points towards it being the sunroof drain more or less, but I'll take a look and report back.

 

I too have noticed this in the past. Since my car is 30+ years old and has been molested by several previous owners, it's unknown if something is missing under the windshield cowl. However, I find the fresh air vent very susceptible to water intrusion...the water sits on top of the HVAC blower box, and when the car shifts it spills all over the floor.

 

I recently had a similar leak. I would definitely check the sunroof drains, but also check your cowl seal to the windshield glass. If there is not a good seal here, water will run into the fresh air vent and eventually spill out of the blower motor (if you have the fresh air door open - recirc can lead to what the previous poster described). I confirmed this was the case on mine by removing the blower motor and pouring a small cupful of water down the windshield.