Air conditioner always on?

it's not so much a matter of mixing in heat as it is shutting down the compressor (i think that's the right term) that cools the air until it's needed again. it would keep blowing 'plain air' at a low fan speed. if it got cool enough, it would switch over to heat.

 

I really would like to see some extensive details on the operation of the A/C. I've been curious if it's more efficient to set a comfortable operating temperature or to manually cycle the compressor as needed.

If the car is modulating the compressor to meet the temperature setpoint without introducing reheat, then that should be the most efficient.

If it's running the compressor for dehumidification, then reheating to temperature then that's less efficient.

The way everything else is optimized on this car I would suspect the program modulates the compressor, but I haven't seen anything to definitely confirm that.

 

i sort of pay attention to the temperature of the air coming out of the vents when i drive, and the compressor does seem to shut off. most newer cars have the compressor set to go on even at lower temperatures if it's humid, to keep the windows from fogging.

i would find it hard to believe that toyota didn't somehow optimize this in the prius considering how much thought they put into everything else.

 

I had read somewhere that the Prius air conditioning compressor actually has two speeds of operation. The low speed is used for general cooling, and the high speed is for max cooling. It's an improvement over conventional belt driven compressors and would seem to indicate that Toyota did provide the Prius with an adaptable environmental control system.

 

in a car, unless its not very warm outside, you will never maintain any kind of cool temperature so the compressor will run nearly all the time simply because the car is warm.

there are simply too many windows in a car. granted the glass has some uv rating to reduce heat absorption, but it aint nearly enough. (although not bad for clear glass it doesnt come close to a good tint job)

to test this thought. turn off the air conditioning and see how long it takes before it starts getting VERY warm. in most cases, the change will be immediate.

another thing to do is put the air on auto. then the fan will speed up and slow down depending on the set point and cabin temperature. realize that all thermostats will have a set range of a few degrees to prevent short power cycling intervals.

 

When ever my windows are up, then my A/C is on! But sometimes the weather is nice, so I put all the windows down and completely turn off the Air.

 

Thanks for the information Rick. Just when I'm totally impressed with the features of the car, I find out there's even more to love about it. It's a lot like an infomercial... "Now how much would you pay for this car? But wait, there's more!"

 

I've just had my Prius for a little over a week (after a 9 month wait), and my previous car had no air conditioning, which I'm used to, so I was trying to figure out how to have just air circulation with no cooling or heating. I read through the entire manual with no enlightenment on the matter, and my dealer was quite unhelpful, saying that it's the "vent" control on the air conditioning menu. I finally figured out (with the help of someone I was giving a "test drive" to!) that if the A/C is off using the control at the lower right that has the fan image on, you can turn on vent only by using the control labedl "A/C" at the upper left. If a green band is showing at the top of this control, the A/C is on. If the band is orange-ish, the A/C is off, but air is circulating.

Why do they make this so hard to find?

 

Kathryn to have just fan with no air conditioning.

first set temp to max cold (otherwise you may get heat)

then hit the AC button on the touchscreen. there should be a green bar above the button that toggles on and off to indicate power. just toggle the bar off.

now you will have just fan. make sure to set the circulation mode to "fresh" for better results.

 

Thanks for clearing this up, Dave. I thought I was delusional when I tried to get "air only" today (I swore I got it yesterday!) and I could only get air conditioning or nothing! There is definitely a tie in with the temp you set (and maybe with the difference between the inside temp and the outside temp?)

 

well setting the temp to "max cold" insures that the heater doesnt kick in which it will if the temp is low enough outside.

i noticed this when i have my air set to 72º but in the morning i dont need it so i just use fan. a few times on cooler mornings i noticed warm air coming through. (you also notice that there isnt a "heater" button) so i guess the heater works automatically when it senses a cooler temperature than the set temperature and the only way to turn it off in all conditions including real cold ones, is the "max cold" setting.

 

A bit off topic but has anyone noticed that when the fan is going at high speed the voice recognition gets very bad. Home or go home is a real buga bear for me. Must turn the fan off or I end up at a Post office or coffee house.

 

Also check out this link to Denso, manufacturer of the airco.