Best Option for Heating/Cooling
 

After going through a partial cooling season last summer, the heating season this past winter, and heading into another full cooling season, I have a question for the forum (my apologies if this has been discussed previously, I couldn't find a thread).

During the winter I found that not using the Auto/AC feature provided somewhat better mpg (although sooooo many other factors could be impacting that) so as we head in to the spring and summer, I am debating using the Auto/AC set to Auto for my air conditioning needs.

I have come to understand the Auto A/C indicator does not mean the A/C is running all the time it just means the HVAC system is operating and so it performs the function of both heating & cooling control automatically (if set to Auto in the control panel).

I figure there are several visitors to this forum that have the computers hooked up and determined if using the Auto process for cooling is more effective, in terms of mpg, versus manual operation. Any thoughts from the data enabled experts?

UTpiper

Re: Best Option for Heating/Cooling
 

I have always kept the A/C off and used it going down hills or when my foot is off the throttle, to keep my mpg up. The Auto function will not take mpg into consideration. It just tries to keep a certain temperature in the cabin.

Re: Best Option for Heating/Cooling
 

I used to use selective A/C use in my Accord but I don't think that's going to help in a Prius. It is electric, drawing power from the battery rather than directly from the ICE. The only impact of A/C on the engine is that it has to run more often to keep the battery topped up. I guess that means different things in the city vs. on the highway.

Regardless, part of the job of the A/C is to keep the HV battery temp within acceptable limits. If you don't keep the cabin cool the battery could overheat and cease to give you the benefit of its presence. Best bet IMO is to use the Auto function but set your temp to the warm side of comfortable rather than the cool side. That way both you and the pack get cooler air but you aren't using excessive amounts of energy trying to make frost in the cabin.