Help!! Crazy nutso berserk heater/AC system!!! (2009 V6)

[2003V8LTD]

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!!

 

[SurferUK]

Check that the cabin temperature sensor is still plugged in and not dirty. It's behind a little grille by the drivers knee. Next to centre diff lock button. Everything there was unplugged when I got mine and it had similar symptoms.

 

[2003V8LTD]

Check that the cabin temperature sensor is still plugged in and not dirty. It's behind a little grille by the drivers knee. Next to centre diff lock button. Everything there was unplugged when I got mine and it had similar symptoms.

Thanks very much for that. It's precisely what was happening. The air sampling sensor and tube were attached properly to the lower dash panel but on closer examination there was no actual wire attached to the sensor. Got out the flashlight, rummaged around for the wire, found it, plugged it back in and good to go.

I mentioned that I replaced the stereo over the weekend ... must've bonked that wire loose while removing a couple of the dash panels! What a relief. Thanks again for your 100% correct diagnosis!!!

 

[SurferUK]

Thanks very much for that. It's precisely what was happening. The air sampling sensor and tube were attached properly to the lower dash panel but on closer examination there was no actual wire attached to the sensor. Got out the flashlight, rummaged around for the wire, found it, plugged it back in and good to go.

I mentioned that I replaced the stereo over the weekend ... must've bonked that wire loose while removing a couple of the dash panels! What a relief. Thanks again for your 100% correct diagnosis!!!

I went through the same range of emotions when it happened to me. :biggrin1:

 

[Seymore Butts]

- this past weekend I installed an aftermarket radio and phone setup; works fine

That's where's I'd start.