Hi all:
My ‘07 with 96K has been a champ mechanically since I bought her in ‘12 but I noticed what looked like dry liquid on my rubber mat under the glove box where something is leaking. Not a ton like 1/4 teaspoon of liquid maybe. Took out the glove box and saw some dry drips on the backside of the box and also in the cabin filter. It’s a gummy brown substance, looks like coolant and I’m suspecting it’s the heater core. So far, I still have heat, not noticing any smells, no smoke. Just wanting to hear other’s experiences with this. Cleaned the dried drips up and going to monitor. Huge job I know so I want to be sure it’s absolutely necessary if I’m going to get into it.
Thoughts?

If it is coolant you should be able to smell it, also if it is coolant it would be pink in color and also most of the time with a coolant leak the coolant will be most often crystallized so you should see some pink crystallization.

The AC evaporator is in the same housing as the heater core, that housing also has a drain line to drain the condensation that forms on the evaporator, I'm guessing that the drain line is clogged and it's now leaking into the interior, if it's clogged it usually would be from dust/dirt that has gotten into there and would explain the color of the moisture/leaking fluid you're finding/seeing.

The AC drain line drains out in the front passenger's wheel well at the rear and near the firewall, it drips down onto the frame rail, on a hot day with the AC running you should see some water draining/dripping down at that location, if not then it's most likely clogged

Thanks for this. I will look into it. It was definitely more of a red/brown gummy substance. Didn’t notice crystallization. Haven’t run my AC in awhile since it’s winter now.

Have you been having to add coolant or notice the coolant level being a bit low?

Not yet. Levels have been good so far. Had the radiator replaced in the last year or so too.

Is it a V6 or V8? Correct me if I'm wrong, but when I look at the hoses on my 07 V6, it looks like the heater core is more in the middle of the fire wall, almost behind the stereo, not the glove box. Did someone maybe spill a little soda? Coke looks brown when it dries. Just thinking out loud here. Toyota coolant should be pink or red.

It’s a 6. Not a spill because I haven t had passengers since I noticed it and there are drips behind the glove box. Going to take AuSeeker’s suggestion and check the AC evaporator drain line. Hopefully it’s just a clog. I had this happen to my 3rd gen but it was gushing out on the driver’s side. 🤞