Losing coolant

[shorelocal]

My '06 Escalade is losing coolant and I'm not 100% sure where it's going. Noticed the coolant reservoir was almost empty, then noticed a pool of liquid on the garage floor that felt slippery to the touch ... definitely coolant. Didn't initially pay any attention to the wetness on the floor because we've had lots of rain and snow, so the truck naturally drops moisture on the ground in this weather. I've topped up the coolant reservoir a couple times now with distilled water and it's definitely leaking somewhere. Oil on the dipstick looks fine .. not milky at all. No smell out of the tailpipe either. No wetness on the passenger side floor, no smell inside the truck when the HVAC is running, and the interior heat seems to blow warm and normal. I left the truck running and looked all over the engine bay and under the chassis ... noticed a drip falling to the floor just behind the passenger side wheel. Looked in the engine bay again and there is a pretty regular drip coming from the heater box drain hose ... that little "L" shaped rubber hose piece just below the AC accumulator.

Question: is this a drain for the heater core? Is this a sure sign my heater core is leaking?

 

[shorelocal]

Did a bit more research and it appears as though that rubber "L" shaped tube is the evaporator drain tube ... guess that doesn't explain where my coolant is going. #stumped

 

[Doubeleive]

Did a bit more research and it appears as though that rubber "L" shaped tube is the evaporator drain tube ... guess that doesn't explain where my coolant is going. #stumped

I'll just tell you like I tell everyone else get a flashlight and a tilting mirror and get under the vehicle and look up.
coolant flows down, so look up
one thing you can try is put some cardboard under the engine area after you get home and check it in the morning, look up from the wet spot
use the mirror to look up under the water pump
check under the radiator area
check the coolant reservoir tank
check the heater hose T's at the firewall

 

[mattbta]

If Wes' post above doesn't reveal the source:

AutoZone rents the pressure test kit with assorted fittings. It's not cheap, but just a hold on a CC. This usually makes it quite obvious.

There's also a dye GM/Delco sell you can pour in and use UV light to inspect after running a few cold/hot cycles.

 

[shorelocal]

Thanks @mattbta ... that's exactly what I did using a similar auto parts chain here in Canada. Slapped it on to the reservoir, pumped to 10 psi, and the leak clearly revealed itself. Turns out it was one of the metal rear heater lines that was rubbing against a wire loom and developed a pinhole leak. Under pressure it was pissin' out. Simple fix in under an hour. Thankful it wasn't something more serious. Cheers all for the responses.