Climate Control

The compressor is electrically driven and comes on only when needed when in Auto-AC. I leave mine in Auto year round and just adjust the temperature a couple of degrees up or down for comfort.

 

I am also trying to figure this out. I think I got it.

I think if you push the Auto button which will make the AC button turn on then push the AC button to turn it off which will leave the Auto button illuminated you can then set the Temp you wish and the AC will not go on and you can set the fan speed you wish. You can not do this from the steering wheel.

I hope my explanation is clear

Mark

 

How do you know your A/C compressor is running? The Prius doesn't cycle a compressor on and off like a normal car. The Prius A/C compressor is electrically driven and proportionally controlled. It can run fast, slow, or anywhere in between as needed. It is also hermetically sealed without the usual shaft seal that often fails. I think you are over-thinking the climate control on the Prius; just set it on auto and let it do its thing. It will run the compressor only when needed.

Tom

 

A lot of folks, like Tom, recommend just leaving it on AUTO and adjusting the temp to whatever you prefer, and let the car take care of itself.

When I first got my car last spring I found this was causing the heat to come on when I didn't want it (which is most of the time). Also sometimes I just like fresh air to come in the vents. So I turned AUTO off. This makes it totally manual.

So now if I want to turn the heat on, I press one of the fan speed buttons and adjust the temp. (A/C button is off.)

If I want fresh air from outside, I choose a fan speed and set the temp to the lowest setting. (A/C button is off.)

If I want to cool the car, I press the A/C button to turn it on and set the fan speed and temp.

I agree that at first I really missed those simple dials, but it didn't take long to get used to the MFD. And I am still able to use the steering wheel controls for temp up/down and turning the A/C on or off.

 

The green A/C light on the MFD means the A/C compressor is enabled, not necessarily running. If you turn off that button the compressor will never run. With the Prius, it's very hard to tell when it uses the compressor, and it's quiet efficient about it. The interior humidity can get a bit high without the compressor, so if you have any fogging problems, turn it back on.

Tom

 

Lots of Climate Control information is available from the search feature.

PriusChat Forums - Search Results

If you really want too much information.

 

First the compressor will never run if the temperature is below 32 degrees Fahrenheit regardless if the light is lit or not (holds true for all cars) and most car experts agree that letting the air compressor run for at least 10 minutes once a month will extend the life of the compressor as it will help keep all the seals from drying out.

 

OK, people have just about convinced me not to worry about the compressor and let the auto climate control do its thing.

I do have a question regarding the above post and the compressor not coming on below 32 degrees (non issue in Seattle)...Why wouldn't it come on in colder temps? certainly the freezing temp of the coolant is well below that??

The refrigerant used turns to liquid @ or around 32F and Liquid cannot be pumped by the compressor, it locks up and breaks.

 

This doesn't sound right to me. The whole purpose of a compressor is to make sure the refridgerant is liquid. Do you have a source of information that says the compressor doesn't turn on at 32 deg.? Do you have a source of information that says that the refridgerant turns to liquid at 32 deg.? Where did you learn these things. I suspect that your source may be mistaken.

 

The compressor squeezes the gas which causes it to become hotter (adiabatic heating). The heated gas runs through the condenser, which is basically a radiator, where it gives up the excess heat and condenses into a liquid. The compressor is designed for gaseous refrigerant, not liquid. All cooling systems have a minimum working temperature, but I can't say what it is for the Prius.

Tom

 

I just wanted to throw in for arf1410's consideration that the Prius climate control system has both a cabin humidity sensor and a solar radiation sensor, both of which are defeated when you turn AUTO-AC off.

While it isn't much of a consideration in temperate Seattle, the HV battery is cooled by cabin air flowing over it and exiting the car. In the middle of a summer heat wave, or driving in the desert of eastern Washington, NOT running the AC can have a bad effect on the battery if it gets hot, which will affect performance and fuel efficiency.

 

As soon as I saw this I realized I made a mistake.

I was typing without thinking it all the way through. I was pretty certain that cooling occured by absorbing heat to evaporate the refridgerant, so I realized that the refridgerant needed to be converted back to a liquid to force the heat out of it. I knew the compressor played a part in that, but I forgot that the condensor was where the heat is dissapated and the gas recondenses into a liquid.

Thanks for the reminder and for correcting my mistake quickly so that people weren't mislead.

I still tend to wonder a bit about the 32 deg. F. temp that was quoted. That still doesn't sound right to me. I'd love to hear from a reliable source what temp the compressor stops working and what temp the refridgerant undergoes phase change under the pressures that are common in the A/C system.

 

That's to avoid condensation freezing on the evaporator. There is nothing special about 32 deg fro the point of view of the refrigerant and compressor.

kevin