# A/C Unit in Teslas



## Asnpcwiz (Sep 26, 2017)

Random question, but what makes the A/C unit in a Tesla so good? I was driving my wife's Range Rover, which also has remote start, and to get the A/C to work it has to turn on the car. Why is it that ICE cars can't run A/C cool off the battery? If the Tesla can do it, I'm lost as to why ICE cars can't. I'm not talking about forever, just for a few minutes or so. But in an ICE car, it just blows complete warm air if it's running on battery.


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## JWardell (May 9, 2016)

AC compressors take a LOT of energy..think of the giant ones in your house and the lights dimming when they turn on. A compressor running off an ICE car's 12V system would probably draw 100 amps and drain the battery and overload the alternator.
Powering the compressor with an electric car's 400V battery means much less current, smaller wires, and though it still takes a lot of power it is nothing compared to the power used by the traction motors that the system is designed for. 
Furthermore, I'm sure Tesla added significant optimizations, a more modern efficient compressor motor, and maybe even variable control.


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## garsh (Apr 4, 2016)

Asnpcwiz said:


> But in an ICE car, it just blows complete warm air if it's running on battery.


In an ICE, the AC compressor is driven by the spinning motor. So the AC simply isn't on unless the engine is running.


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## Oregonian (Dec 30, 2017)

garsh said:


> In an ICE, the AC compressor is driven by the spinning motor. So the AC simply isn't on unless the engine is running.


And the clutch is engaged.


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## mishakim (Sep 13, 2017)

This was one of the major reasons the auto industry planned to (or at least talked about) move to 42 Volts for the core electrical systems - things like the A/C compressor could be run by electric motors instead of belts off the ICE. It never came to pass for all sorts of reasons.


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## JWardell (May 9, 2016)

mishakim said:


> This was one of the major reasons the auto industry planned to (or at least talked about) move to 42 Volts for the core electrical systems - things like the A/C compressor could be run by electric motors instead of belts off the ICE. It never came to pass for all sorts of reasons.


it IS coming, though, a few manufacturers have "mild" hybrids coming soon with a 48V system on the alternator/starter that can add a little extra torque. I bet some of them will also be powering the AC compressor with that.


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