LexRexBlue

On the RX 400h the air conditioner control is hidden under climate. Now that the weather is colder, are you running the ac all the time? Turning it off? Does it stay off if you click Auto? Now that it is fall, the set temp seems to vary up and down. I find myself switching it up and down every few minutes. Anyone else experiencing these fluctuations?

Booyah

When I hit Auto I go under the climate and turn the AC OFF and go from there, so I only have heat and no AC addition.

katzjamr

I agree with Booyah, every time you hit 'auto' the ac will be on and you must turn it off from the climate screen. I also find myself doing alot of temp adjusting in the cooler weather perhaps im just impatient., in addition im using the heated seats for quick warmth. Its been cold in seattle. And yes my ICE is running longer in the am, and short trip mileage is sufffering more. Longer trip mpg is still great.

LexRexBlue

Thanks I feel vindicated. I thought I was going crazy. NJ weather is sort of like WA weather right now. Today I drove my old RX and really felt the difference in temp. between the 2 models. I have to say in this weather the old RX felt better. Maybe the system can be tweaked. I'll ask when I bring it in for its 5000 mile service.

rxdriver

I've noticed that it's sometimes too cool in my 330 as well during the fall.
I think the problem is caused by sunlight. In addition to sensing the air temperature inside the car, there's also a sunlight sensor on the dash. The climate contol system tries to predict how much heat the sun will add, and turns up the cool air to compensate in advance of a rise in actual air temperature. This time of year, there's enough sunlight to make it seem bright outside, but the sun really isn't at a high enough angle to heat up the car as much as the system thinks it would. My solution is just to turm up the temperature setting a little bit, and then it seems fine.

Also note that whether the A/C is "on" or "off", the compressor will not actually run if the outside temperature is below 33 degrees F. The dash might say it's on, but it's not really on if it's that cold outside.

SteveRX330

I've recently gone through the identical thought process of regulating the heat, but with the A/C turned off. As mentioned by other responders, I've initially set AUTO ON and then gone in to Climate Control and manually turned the A/C OFF. What I have noticed is that the airflow will automatically vary depending on cabin temperature. Initially, all heat is directed to the floor vents, but after the cabin stabilizes the airflow is directed bi-level. Similarly, the fan speed will vary depending on the variance between outside temperature and cabin temperature. The lone exception is that on some of the recent colder mornings/evenings I've manually increased the fan speed rather than waited for the car to warm itself up.

Steve

salimshah

Two things about A/C (cooling part of air conditioning) in winter time ..

1. You must run the A/C frequently (min frequency not published ~ once a week). There are seals in the system which get lubricated when the system runs. If not run, the seals dry off and will cause early system failure.

2. A/C cooling,not only provides cold air but also removed humidity from the cabin air. The term Air Conditioning is pretty comprehensive ... hold, cold and moisture level too. In winter, to prevent or remove quickly the inside window fog up, the A/C helps tremendously. The themostat and the clutch on the compressor takes care of turning the compressor of, when not needed. The AUTO setting on Lexus is far superior [imho] than other vehicles. The defrost button kicks in the compressor when needed.

You can override the auto, but the auto is fairly smart. The green light lit, means the compressor is being cntrolled by temp setting.

Talking about air conditioning, have you observed that cabin fan in auto does not go full blast till the coolant temprature reaches a certain temprature level? This is doen to help engine reach the optimimum operating temprature quickly and reduce emissions.

Salim