[SoCal LS-L]

One thing ive noticed about the SVX climate controls is that they stay in whatever position they were in before being turned off. If I had my heater on at one point, the climate controls will allow fresh heated air blow into the footwell even when the system is turned off. Im not sure if this applies, but if you push "Circ" after you start the car, it will block the fresh air from blowing through your heater core into the cabin. You can also set the system for the lowest temp (I think 65') before turning the system off, which will route the air around the heater core and just let in fresh cool air while you drive. Worth a try before suspecting the trans.