We just purchased a 2009 Limited 4wd V6. It's a nice truck and we've owned it for about 3 weeks.

Today the strangest thing started happening: something between the heating and a/c went completely insane!! I don't know if the culprit is the climate control box or something more profound than that. Here's what happens:

... the heater always stays on full blast at any setting above "LO". On "LO", you just get full blast A/C. At anything above that, the A/C gets overpowered by a blast of heat. But very strangely it will switch vents and suddenly send it down into the footwells or some other odd thing. When it's 90 degrees out, one definitely does not need heat in the car!

I checked the connector on the back of the climate control box and it seems to be normally attached.

Two things that I suppose might somehow have _some_ bearing on this:

- last week I had the radiator coolant flushed at a Toyota dealer. Seems fine; temp gauge stays in normal position
- this past weekend I installed an aftermarket radio and phone setup; works fine

I hadn't really driven the car since these things were done, before today.

Any idea what in tarnation could be happening? This is one of the strangest things I've ever seen happen in any car, ever!!