Auto A/C settings

Very good question.
I, too, would like to know the answer.

 

I have also wondered about this. However, I can say that the last few days I have needed to heat the car, and if the compressor is "enabled" than the motor will stay running at a stop. If I switch it off, then the motor goes off as well.

I therefore concluded that it stays on in automatic. I would love to find Im wrong here!

 

[font=Comic Sans MS:4a7ae9a4e3] That certainly makes sense. But consider this:
It's recommended that the A/C compressor be "On" while heating
the car if the windows are fogging up.
The A/C compressor removes the humidity from the air and helps defog. (Is that a word?)

 

If the climate control is on auto the windows will not begin to fog. The Defog buttons are for use when you get into the car and the windows are fogged or frosted.

 

This is a feature of most cars with Auto A/C. The good news is you can have it changed (among other things)by your dealer via the Toyota Scan Tool. It will allow you to select Auto A/C without automatically engaging the A/C compressor if it was not already engaged.

The compressor cycles on and off to reach and maintain the desired temperature whether heating or cooling the air. It prevents window fogging because it is actually removing moisture from the air. The only time the compressor will not run (even though the A/C icon is lit) is when the ambient temperature is below 38F. This is to prevent damage to the system because the refrigerant will become too cold.

I hope that helps a bit.

Best,
Pino

 

Isn't the air conditioning compressor on the European model of the Prius electrically driven?

Before the weather turned, I have had the air conditioning on full blast in 100+ degrees Fahrenheit ambient temperatures and the ICE would shut off every time that I came to a stop as long as the traction battery was sufficiently charged.

 

heating the outside air will also reduce the moisture content too.

 

Does the electric a/c unit in the Prius actually use a compressor? I was discussing this with a friend today and he mentioned that some A/C systems use electrical resistance to create a heat transfer. In fact, the refrigerator on most RV units don't have a compressor. If the Prius does use a compressor, does it get its power from the main electric motor or would it have a separate motor?

 

The Prius uses an electric compressor which is driven by an integrated motor.

Denso Electric Compressor for New Prius (Click here)

 

Unless you select the "Defrost" mode, the air conditioning compressor is thermostatically controlled and is automatically turned on and off on as needed basis.

 

This discussion raises the question regarding heating cabin air. We, at least in NA, typically use the phrase "air conditioning" to mean cooling. But what about heating the cabin? The engine coolant is not always available for routing through heating coils with the Prius as it is with normal cars. Is it possible that the compressor is functioning as a heat pump, ie. with both a cool cycle and a heat cycle? If so, then the system would always be enabled in AUTO, with the thermostat controlling the decision to heat, cool, or remain in standby depending on cabin temp.

The Denso article only mentioned "air conditioning." However, literally speaking, you can consider that cabin air is also being conditioned when it is heated. Does anybody own a Prius Shop Manual? I assume the section on cabin climate control would describe how the system is designed to operate....?

Hank

 

no. in some circumstances it is possible to have both the air conditioning and heater on at the same time when using defrost.

realize that because the compressor runs only when a demand for cooling is called for means that although the air conditioning system is on, it will be using minimal energy.

 

Oh, OK. I was thinking that heat strips being an inefficient use of power, Toyota would have specified something more efficient like a heat pump. Probably the cost of a pump is still too high though....?
Thanks, Hank