Richardgil

Ls 460, or for that matter any vehicle with automatic climate control, when the temperature setting is higher, warmer, does the compressor run less?

Spudo769

I have no idea, but my guess is that the compressor runs about the same, but the fan speed a lot less.

Tec80

Yes, the A/C compressor will run less often when the interior temp setting is higher.

Flanker271

My understanding is this: When the A/C button light is illuminated with the full automatic climate control, the light merely indicates that the compressor will be available if the system dictates that it is needed to maintain the interior temperature/humidity settings set by the user. For example, if the automatic climate control system senses that the interior of the vehicle has too high of a humidity level, it will run the compressor to lower the humidity, regardless if the outside air is cooler than interior. If you manually turn off the A/C button, then the compressor will always be 'unavailable' thus the automatic climate control will also turn off, since it can't regulate the interior air conditions without the compressor.

In very hot summers, if you go stand outside beside the idling vehicle, you can sometimes hear the A/C compressor cycling on/off even when the A/C is turned on.

I usually just leave the full automatic climate control turned on. The system can manage various parameters much more efficiently and effectively than us humans can.

N3VR4G3T

Since its kind of part of this topic, I have to say my 08 has the best auto climate control I have ever used. My other cars seam to have the fan blast you are full blast and is either on full blast or off. No happy medium. The Lexus gets do my desired 71 very quickly and doesnt blast me...

Flanker271

Adding to this, the automatic climate control is also smart enough to control air flow through different vents depending on ambient temperature.

I'm from Cincinnati OH and the average day temperature fluctuation here is huge, especially in September and October. During those months, in the morning when it is 40-50F outside, my automatic climate control will only output airflow through the floor vents until the air warms. It will then gradually transition from the floor vents to the center vents and I'm greeted by a stream of cozy warm air. I never feel any cold air draft blasting at my face. The interior remains very comfortable at all times. During lunch time when it is 70F outside (around 90F inside the car when parked outside), the system will directly send cool air to the center vents to cool down the cabin quickly. It also automatically turns on the recirculate function.

The Lexus automatic climate control system works much better than the Acura automatic climate control system what I had previously.

Oliver Enterprises

Flanker271 - The A/C system is not supposed to cycle OFF/ON like you mentioned. It does this because the low side pressure reaches a low limit threshold and the low side pressure sensor trips and the compressor is turned off to prevent further lowering of the pressure. Which would lead to the evaporator freezing, and prolonged evaporator freezing leads to bigger problems. A cycling of On - Off - On is an indication of low refrigerant. 90% or greater problems with a vehicle's A/C system problems start with low refrigerant. The systems take a beating in a car, so it's by far the most common problem to have. A large portion of my time spent in automotive as a design engineer was spent working with A/C systems. At least the mechanical aspect (compressor, evaporator, dryer, condenser, etc) and how the system worked. Not so much the HVAC, meaning the blower and logic of the HVAC.

As for the topic at hand. I don't believe the A/C system even in our vehicles to be so "intelligent." It's a good system regardless. But, when in the ECT switch is in the PWR, Normal, or Snow mode, I'm guestimating that the compressor runs at its max duty cycle. And the temperature is controlled by how much warm air from the heater core is blended into the chilled air. However, when the ECO mode is selected, this has the ability to derate the compressor duty … thus having some ability to conserve fuel. These are my opinions and understanding. I don't know the fact of the matter.