Hi, my rear a/c does not blow cold in my 2001 toyota sequoia. What can it be? The front a/c is blowing cold. I took the R/R cargo panel off be the rear evaperator/heater core. I felt both pipes going into the heater core, they are hot. I felt the small pipe going into some valve (right before it goes into the evaperator, and that pipe is cold. But the pipe coming out of the evaperator is not cold at all.