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Re: Revisiting the A/C on while on auto

Posted: Tue Nov 04, 2014 3:59 pm
by dmen
Wattsup:

The high temp here was about 50; cloudy all day so no solar radiant warming of the cabin. When I turned on climate control set to LO auto with no vent override, A/C defaulted to off, and climate graph showed no power draw. I have seen A/C default to 'on' in the same settings when the ambient temp was high 60s or above. So yeah, ambient temp seems to be taken into consideration in determining what LO does. But it's not like a numeric temp setting in the important detail that the heater should never be engaged in LO. If you set it to 60 and it's 20 degrees outside, the heater will run. If you turn it down one notch to LO, the heater will turn off. Same goes for HI. If it's 110 degrees in the car, HI will still turn on the heater. LO only cools, with cold outside air or a/c-chilled air; HI only heats; all numeric temp settings will heat in some settings and cool in others.
Other observations:
In cold dry weather, when I have climate set to LO and then select defrost vents, the climate power draw bumps up to 1 kW for a minute or so, then waxes and wanes every minute or so. It's presumably toggling the A/C, though the A/C indicator shows itself off. If no vent is selected or the panel or floor vents are selected, climate energy use remains 0.
I also think humidity plays a role in how the climate control chooses to act in LO. On a 55 degree very wet day, my LO with A/C supposedly off climate power draw was 1-2 kW with no vent, defrost vent, and floor vent selected. Only panel vents used no extra power.

I would guess these controls behave identically in Ford ICE cars. I know simple cabin heating is a much larger energy draw than the occasional unwanted A/C use, but I would still like to see a climate control system that makes more sense in an EV. A more efficient heater would be huge; an electric windshield defroster, an A/C off setting that does what it says and doesn't reset randomly, and a simple one-button 'outside air vent' would help as well.

Re: Revisiting the A/C on while on auto

Posted: Tue Nov 04, 2014 4:10 pm
by hybridbear
dmen wrote: I would guess these controls behave identically in Ford ICE cars. I know simple cabin heating is a much larger energy draw than the occasional unwanted A/C use, but I would still like to see a climate control system that makes more sense in an EV. A more efficient heater would be huge; an electric windshield defroster, an A/C off setting that does what it says and doesn't reset randomly, and a simple one-button 'outside air vent' would help as well.
Ford offers an electric windshield defroster on the Transit van. It was previously discussed online here: http://www.myfocuselectric.com/forum/vi ... f=5&t=1594

Re: Revisiting the A/C on while on auto

Posted: Tue Nov 04, 2014 4:54 pm
by WattsUp
dmen wrote:Wattsup: The high temp here was about 50; cloudy all day so no solar radiant warming of the cabin. When I turned on climate control set to LO auto with no vent override, A/C defaulted to off, and climate graph showed no power draw. I have seen A/C default to 'on' in the same settings when the ambient temp was high 60s or above. So yeah, ambient temp seems to be taken into consideration in determining what LO does. But it's not like a numeric temp setting in the important detail that the heater should never be engaged in LO. If you set it to 60 and it's 20 degrees outside, the heater will run. If you turn it down one notch to LO, the heater will turn off. Same goes for HI. If it's 110 degrees in the car, HI will still turn on the heater. LO only cools, with cold outside air or a/c-chilled air; HI only heats; all numeric temp settings will heat in some settings and cool in others.
I get what you're saying. My comments were only in relation to the "auto A/C" behavior. Thanks for the more complete clarification about cooling/heating and LO/HI.

In any case, regarding just the A/C again... it definitely seems like ambient temps below 60 keep the A/C from coming on with "fan low". The other day, the temp was 57 and the A/C did not come on. This was my second confirmation in recent days that "somewhere below 60" is what keeps the A/C from turning on.

So, although, as you say, "LO only cools", it does seem that the system (when set to LO) considers 60-ish the "coolest" and, if the outside temp is already below 60, it won't run the A/C automatically.

This finally explains (for me anyway) why sometimes (usually in the summertime) "fan low" always turns on the A/C and sometimes (usually in the wintertime) it does not. It always seemed "random" before, but now the connection is obvious.