It looks like I am leaking coolant from a weep hole in the passenger side of the firewall. The fluid is actually black-ish in color, but evaporates quickly and only leaks intermittently. My coolant level is quite low in the reservoir, but still bright pink (not black-ish).



Fluid leaking from small hose in passenger side of firewall...

The only other time I've lost a heater core it was obvious (coolant smell inside vehicle, steamed up inside windshield and a mess of coolant everywhere).

From my searching on this forum, I can see this is quite an endeavor, so I'd like some confirmation before I take the dash apart on a couple of things:

1. Does this appear to be a leaky heater core?
2. What else should I plan on replacing while I've got the dash/HVAC out?

I've got a nasty vibration when the blower motor is on high so I've been wanting to tear in to the dash anyway, but I'd like to be sure this is the heater core before I take the time (and spend the money). Thanks!

 

That looks like the ac condensation vent. Heater cores usually leak inside, on the passenger floor board. You could do a pressure check on the coolant system, and check for leaks.

 

So, potentially unrelated then.

Well, whatever is coming out of the vent is more than just water... or maybe I'm picking up some grime from the engine compartment, but it's more water than I'm used to from A/C condensation. That would make sense though since it doesn't look like coolant coming out.

I'll do a little searching and figure out how to pressure test the cooling system.

 

Well the amount of condensation depends on the weather, how many people are in the vehicle, etc.

Throw five hot sweaty bodies in a car and the relative humidity inside the cabin can spike (foggy windows). When that warm, wet air hits the cold surface of the evaporator it condensates on the surface. That excess moisture is channeled outside through that tube you see. IIRC the design of the box usually means you'll get coolant running down the floor vents up front, wetting your floor mats/carpets in that area.

A hot humid day will cause the AC to draw buckets of water out of the air. If the tube is partially clogged it may sit inside the HVAC unit until the vehicle angles a certain way or the fluid otherwise finds a path out.