standing in front of the vehicle, it will be on the left on the fire wall. two hoses go through the wall to the heater core. one has a cable controlled valve on it. that's it!
lookie here,
http://www.autozone.com/autozone/rep...96b43f8038021c
that's a FREE online manual for your vehicle. just have to sign up. plug in vehicle info, and go to "repair info".
-------------
EDIT,
not the first time autozone was incorrect.
then it has to be under the dash. the two hoses should go through the wall, enter the cab, and immediately go into a box (heater core). just b4 the box will be the valve on one of the hoses.
sorry, that's all i can find. if you look at the manual, it shows a control servomotor. but all sources (be they incorrect) show the valve in the bay. i'm guessing it's under the dash, center, or you don't use one. but i don't think that's the case. frickin hard to get to.
if no one else chimes in here, and yo haven't figured it out, i suggest you go here,
http://www.toyotanation.com/forum/
sign up and post in the 8th gen corolla forum. great ppl. been a member for years.