Auto mode for heat & A/C question

Makes sense - remember that heat rises, so you put it in low, and the warm air being lighter than the denser, cooler air, will tend to move up! (basic Physics!)

 

Not sure about your Prius, but on our 2013 Model Three there is a button on the flying bridge that has a couple of arrows and the defrost symbol. If you push that button the system will change the flow from one location to the next. It is another one of those items that can be overridden such as I described earlier ie: fan speed, recirc, etc.

When ever you override part of the system it will stay over ridden UNTIL you hit auto again. Once you hit auto, everything will revert back to the default settings.

 

Remember...HEAT RISES.

 

yup, and cold air falls... like Wil said "basic physics".

 

if you change the air flow while on auto, doesn't auto shut off?

 

Right, the Japanese engineers do not want warm air in the driver's face. Even if the A/C lamp is ON, it may only be cycling on oh so slightly ( its called duty cycling; it runs the compressor on and off many times a second; more on than off increases compressor speed, less on than off slows compressor speed). The HVAC controller computer looks at humidity, outside temp and sun load, interior temp. It then says, to get to the operator selection what needs to be turned on and off.

Its a very sophisticated system, as I said before. If you don't want A/C just turn or put the button off. It will still try to get to target temp.

And for the rest of us, it's not a bad idea to cycle through your different modes to exercise those HVAC doors, say once a month. They need to move, just to keep all of them working.

My Recirculation door will do a "click click click" noise at times. A simple push of the button cures it. Then, I push it again and no clicking. But eleven years of almost daily use, I am not complaining. JTM

 

Nice thread about the sophisticated operations of Prii life support systems (a.k.a. Auto A/C). Discovered a lot of stuff I was rather vague about and will be trying in damp old London during my commutes this winter.

Thank you, everyone!

SM-G900F ?

 

Remember - It's not the heat, it's the humanity...

 

For what it's worth, I just leave everything in Auto (including the A/C button) the year round and just adjust the temperature as necessary.

 

Through summer I use mostly roll-the-windows-down Mode, either a bit, or more, or fully, depending on speed, temperature, etc., with ventilation system shut right off. At high speeds, I'll turn on the vent system, roll the windows right up, or leave them slightly cracked. Very occasionally will use A/C. You do want to use A/C once in a while, to keep the oil circulated.

On cooler days, or getting into wet and chilly winter, I'll roll up the windows and run mostly Auto with A/C off, if it's raining and fogging up I'll set mode to heat/defog. The latter kicks in the A/C surreptitiously, off and on, regardless of how you have the A/C button set. If it's a lot of bodies piling into the car with wet clothes, rain really coming down and the cabin getting overwhelmed by humidity, I'll expressly turn on the A/C. I'll try to run the last few block before shut down without A/C, to give it a chance to clear humidity of the chiller unit (not sure of the correct name).

 

That would be the evaporator, a heat exchanger in which refrigerant evaporates to extract heat from the air (thereby condensing water from that air).

A last few blocks without refrigeration might not clear the residual condensation in cool rainy weather, but on a hot day should help.

The programming of the "AUTO" mode makes smarter decisions than the average human operator most of the time, but occasionally it does annoying goofy things. For example, it sometimes switches unexpectedly to unwanted heat on slightly warm days when I choose to use the compressor sparingly. It needs a specific HEAT button so heat can be positively shut off, the same way AC can be (except in defog mode).

 

For the most part, I leave mine at 71 and roll with it. Cold days, I will raise it to 75. If the wife is with me, I add more fan for her.