warm air...how?

The early generations had an electric heater to just supplement cabin heat until the engine warmed up. Efficient engines take longer to make waste heat for the cabin. The gen3 introduced the exhaust heat recovery system that warmed up the coolant faster, so the electric heaters may have been dropped then. With the PiP's limited EV use, Toyota likely took the 'use the engine for heat' approach. Some PHEVs today still do that.

With a heat pump, there isn't that delay waiting for coolant to heat up before feeling it in the cabin. Even on cold days the heat pump will make some heat through compression of the refrigerant. On really cold days, a home unit will have electric back up, but a PHEV has the engine for that. The engine is also there for the shortened EV range cold causes, so I don't see why Toyota would bother with electric heaters in addition to the heat pump. They'll just further shorten that range, or be too low power to bother with the effort.

 

PTC heater still present in gen3, at least in the US.

 

No electric heat in the gen5.

Crown has the IR knee warmers as an option, but the Prius only has the ICE, while the Prius Prime has the ICE plus the heat pump.

 

I monitored AC WATTS with a Scangauge II, one thing I noticed: when vent mode was set to direct air to feet and windshield, the AC compressor was cycling surreptitiously, without the AC button being pushed (lit). This is Canadian spec vehicle, may be a factor.

 

In some vehicles(not just hybrids), the AC compressor cycles when using defrost to dry out the air hitting the windshield.

 

My US one is the same. The A/C has a dehumidifying effect, used either when you have the full-blown front defog button pushed, or when you have the feet+windshield mode selected.

It comes back to the car being computer-controlled with your inputs used for guidance. There is nothing about the "A/C button" that forces the car to do or not do anything. The car runs the compressor whenever it has a good reason. The button lets you express your opinion on whether just keeping you cool counts as a good reason.

The LED in the button doesn't tell you when the compressor can be used; it only acknowledges your opinion you expressed.

 

And, in some cases, the car say "Buzz off. I am in charge". There are many safety features on the newer models that turn back on when the car is restarted, even though there is an option to turn them off.

 

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