I'm starting my second week of Prius ownership and am still learning about the car's ins and outs. One thing that I'm trying to do is to minimize the use of the air conditioning to improve my fuel economy. It seems that to get any kind of heat you have to have the AC 'on' with a resulting impact on your MPG stats. On my more mundane vehicles it was possible to turn off the fan, enable vent mode and adjust the heat to suit your tastes. Is there a way of doing this on the Prius?
I'm not sure about getting a true "vent" mode as I do in other Japanese cars. What we do though, is shut the AC off on the MFD, and just put the blower on low and put the heat setting to about 74. You'll know the AC is off if the yellow bar above the words is grayed out.
Keep in mind that the air conditioning compressor does not run continuously even with the A/C button illuminated. The yellow bar under the button just means that you give the car your permission to use the compressor if it wants to. Also, in addition to cooling, the compressor is also used for dehumidification and might help in keeping the windows from fogging up. With AUTO A/C showing on the dashboard, if you press one of the fan speed buttons, you're telling the system to adjust whatever it wants, but don't change the fan speed anymore. This could be a problem during really cold weather when the car is trying to keep you warm but you've told it to keep the fan on low. It might be necessary to increase the airflow just to get more heat into the cabin. The programming for the climate control system is actually quite good. It won't blow cold air onto you until the car warms up some, and even then it gradually increased the airflow as the engine temperature increases. After the system has gotten close to your temperature setpoint, it will reduce the fan speed so that it doesn't seem drafty. Disengage the A/C button if you want to, but I'd recommend that you let the system pick the appropriate fan speed. BTW, just like the fan speed buttons, you can also press one of the airflow direction buttons, which tells the car that you don't want it changing that either.
Yeah, I agree with the above posts. Though sometimes people debate this point, I stand to believe that the Auto A/C setting causes my ICE to run more. Therefore - right or wrong - once the interior is where I like it, I turn off the Auto A/C and go straight to vent using the instructions Mike gave. But as 8AA pointed out, on humid days the windows will fog and I'll turn the A/C on again.
I have taken to leaving the AC on Automatic, setting the temp to 78 degrees with med to high fan speed. These settings work fine for Sacramento summers and of course trip mileage is still 50mpg plus. At 60MPH.
