Another quick question.

If I understood it correctly, Click and Clack once explained that the a/c compressor in a regular car runs continuously (compressor clutch engaged) when the a/c is on. If you felt slightly cold and pushed the temperature up a bit, the car would simply run some air through the heater coil to mix with the cold air. Assuming that is the case, bumping the temperature up didn't give the a/c compressor any relief, the a/c clutch was always fully engaged regardless.

Does the TCH a/c work that way or does the compressor start and stop depending on the cabin temperature - like the a/c compressor in our house? Given that it is an electric compressor rather than belt driven, that seems reasonable. It would also follow that gas mileage would be slightly better if the compressor were to cycle on and off as needed. Thus, maintaining a cabin temperature of 70 degrees would likely yield (slightly) better mpg than 65 degrees. Yes?

Thanks again. David

 

The TCH and similar hybrids and EVs that use electric ACs also use variable speed compressors that run at the speed necessary to meet the cooling needs at the time. Of course there is a limited amount of adjustment possible to keep the system working, but that is less of an issue than with accessory belt driven compressors that must turn at speeds dictated by the engine speed, from just above idle (idle kick-ups are used when the AC is on) to engine red-line. Because the electric compressor is always running the "right" speed for the cooling needs, completely independent of the engine speed, the compressor can be smaller and more efficient. That is because it doesn't need to be big enough to provide enough cooling even while the engine is just above idle. The electric compressor likely would be used in most all vehicles, but is only efficient when high voltages are dependably and efficiently available, as is the case in most hybrids and EVs, but not ICE vehicles.

 

You answered the question very well, Alan. Thank you.