bornking

I didn't want to piggyback off another thread about the temp sensor (as it may not be the cause of the issue), so here we go:

2000 LS400
211,000 KM

Regularly serviced.

Yesterday the HVAC was acting strange:

When I set it to 29C or below, cold air comes out, (perhaps warmer at the footwell, but still not 29C).
When I set it between 29.5C and 32C, warm to warmer air comes out, but not hot as usual.
When I set it to HOT, hot air comes out, but not at full speed (with the fan set to max).

When I set it to Auto Temp, and try anything below HOT, the AC comes on and Cold Air comes out (not as cold at the footwell).

So either I set it to 29 to get lukewarm air, or HOT to get hot air.

Note I just put on a used cat onto the passenger side...not sure if that matters.

What can it be?
I am no HVAC expert at all, but from the threads I've read perhaps it is:
- Temp Sensor under steering wheel?
- Heater valve?
- Ducting issue (maybe where hot and cold air mix?)?


It's been two days now and still the same thing.
I am ready to look at the temp sensor under the steering wheel assuming I have the tools.