I assumed that Oldfox was referring to the cooling compressor. If the Prius used a heat pump A/C system the compressor would then be used for heating and cooling. Since this is not a heat pump system the compressor is only working when cooling or defogging.mrv said:AC is short for air conditioning.
you can run it for heating or cooling.
it is used to dehumidify the air.
(it is automatically run if you use the front windshield defroster/defogger.)
On the 2004 Prius, if you choose the "Auto" setting, it always uses the AC...
Oldfox, your A/C compressor will not come on in "auto" mode unless you have set the temprature low enough to require cooling.oldfox said:Computer problems have kept me from responding (New Motherboard)
Appreciate your comments but am still a bit confused. I have a 2004. If I read your replies correctly, The A/C is always on when in auto mode but must be turned on if in manual? In other words, I can heat the car without A/C as long as it is in manual mode?
If above is true, i wonder why Toyota would do this (Always have A/c on in auto mode) Isn't the A/C a drain on batteries?
TCBRT, I am confused by that statement and can not find that information in my manual! Could you explain how a cooling compressor could be on and not cooling? By the way, dehumidifying is a product of cooling. You must cool air in order to condens the moisture out of the air. If windshield defogging (dehumidifying) is needed in cold weather, both the cooling compressor and the heat are on together. The compressor is on to dehumidify (and it has to cool to dehumidify) and the heat is on to offset the cooling effect from the cooling compressor! Kind of like Nixon having the fireplace going in the summer and using the air conditioning to keep the house cool at the same time!TCBRT said:If you press the "auto" switch, the AC compressor motor is running whether the connected compressor is cooling or not. It can be used to de-humidify if needed.