heating adjustment out of whack (1 Viewer)

[OregonB]

Can't figure out what's causing my cabin heat to not adjust +/-. Whether I set the cabin temp at 75 or 68, it all ends up getting too hot eventually, like it was set to max.
Once you get down to 65, the A/C (I believe) kicks in. So it's either one or the other (I have the Nav display)

 

[PcCruiser]

I have non-nav and I have the same problem. Except that I'm either at maxed hot and anything below (even at 70 something) and it goes cool.

There is a regulator (air mix servo) that may have gone bad or you may have an issue with one of your cabin temperature sensors.

This thread has some good info.

A/C Issue

 

[Mark WV]

I had the exact same issue on my 03 LX last year - Either too Hot on any setting above 66 or Max AC (to cold) were the only two results that came out of the vents.

I tried replacing both the cabin temp sensor and the exterior temp sensor - no change.

So after a week at the dealership and factory support to trace it down, it turned out to be the AC AMPLIFIER (not sure why it is called this, as it apparently is the computer box that regulates the automatic temp controls.)

Looks like it is available on several lexus parts websites for $440. or probably significantly lower from a salvage yard.