Climate Control Use Of Recirculate

[patt]

The weather had turned beautiful here. Cool enough that we don't need to use air conditioning which has been doing great for our gas mileage. However, every time I start the car, the automatic AC turns on the recirculate mode - which means that it blows warm air until I remember to switch it to bring in outside air.

Is there a way to disable it from using recirculate? I can't see why the automatic system is choosing recirculate since the outside temperature is cooler than the the inside of the car and the car is hotter than the temperature I've got it set to maintain. A sensible autormatic program would see that the car is hot and the outside is cool so it should want to bring in outside air to cool the inside. I've even driven for a while to see if it was some start up thing where it would change later but it doesn't.

With the air conditioner off, we are getting close to EPA numbers. The two tanks so far were between 28 and 29 mpg (by calculation, the number from the car's monitor is about 1 mpg high fairly consistently). With air conditioner load off, the highway and city mileage are back in the right order - I've been seeing about 27 mpg for highway cruising between 55 and 60 mph dropping a mile or two per gallon when the speed goes into the 65 to 80 mph range; 30 mpg and up for city driving (not awful stop and creep but closer to the EPA test of a stop every 1/2 mile and peaking at 25 to 45 mph between the stops).

[katzjamr]

First of all let me say Patt you are one hell of a hybrid driver, my consistent mpg is 26 to 28. Also i am doing this from memory but it seemed to me when i had Lexus set personal settings there was some way they could set the AC to keep from going to recirculate first. The reason i keep it off (unless im following a diesel truck or i need max cooling) is the fans are quieter in the recirc off mode.

[JasonATL]

I have experienced the same. I do not know of a way to keep the recirc from coming on. However, you mentioned the cooler air outside than inside. Note that the A/C is an INSIDE climate control system. So, all that matters to it is the inside temp (that is actually an oversimplification). The reason the recirc kicks in, from what I've experienced/observed, is that it senses an extremely warm interior and its default is to cool the interior as quickly as possible using recirc. I agree that the brainy folks at Toyota/Lexus ought to be able to solve this one.

In the meantime, I've found it helps substantially to use the remote "all windows open" function as I approach the car. On a breezy day, this will cool the interior enough so that the recirc won't kick on.

[patt]

First of all let me say Patt you are one hell of a hybrid driver, my consistent mpg is 26 to 28.  Also i am doing this from memory but it seemed to me when i had Lexus set personal settings there was some way they could set the AC to keep from going to recirculate first.  The reason i keep it off (unless im following a diesel truck or i need max cooling) is the fans are quieter in the  recirc off mode.

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Actually, it is a combined mpg figure for my husband and myself. Driving style contributes, but there are some additional factors. During these last two tankfuls, we have mainly been driving our usual commutes which are about 15 to 18 miles and very few short 1 to 6 mile trips which pull the mpg down. Our commutes are about 10% freeway and the rest mostly uncongested suburban driving which seems to be a pretty sweet spot for the performance as long as we don't hit too many red lights. If our area had synchronized lights instead of sensor based lights, we would probably do even a bit better.

The second tank also included a 260 mile round trip on the highway, but Bay Area congestion kept the speed down for some of the trip or the mileage wouldn't have been quite as good.

For comparison, during the summer AC load we were pretty consistantly getting something between 25 and 26 mpg on a tank.

[Statman]

Is there a way to disable it from using recirculate? I can't see why the automatic system is choosing recirculate since the outside temperature is cooler than the the inside of the car and the car is hotter than the temperature I've got it set to maintain. A sensible autormatic program would see that the car is hot and the outside is cool so it should want to bring in outside air to cool the inside. I've even driven for a while to see if it was some start up thing where it would change later but it doesn't.

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Yes there is a way. Go to the dealer and request the LPS (Lexus Personalized Settings). Option #12 is whether you want recirculating or not to be automatic (On is standard off or manual is optional).

[SKperformance]

General maintance has a full list of Cbest options (lps)