Explaine how the heater works

That is NOT the only reason. See Why mileage gets worse in winter | PriusChat.

 

^^^
I did read it completely. You still made an incorrect assertion that "heard that the mileage drops in the winter due to the ICE having to run to heat the car". That's not the only reason.

I can't answer your question though. Then Gen 2 and 3 Prius have some supplemental PTC heaters (Electric Heating Elements for those cold mornings | PriusChat and PTC HTR ? | PriusChat).

Also, on Gen 2 and 3 Prius, the ICE does NOT need to run to provide requested cabin heat. It only needs to run if the engine coolant temp is too low for the given amount of heat demanded. I've confirmed similar behavior on other Toyota/Lexus hybrids and the Altima Hybrid (why the engine keep running but no charging and no driving? | PriusChat).

2011 Prius c? No such thing....

 

The car does have electric A/C, and using it "in reverse" as a heat pump is within its capabilities, but I haven't read anything about that in the brochures. I keep an eye on my battery amps and coolant temperature, and I've never seen the car use electricity to heat the cabin. But then I don't have any big mountains around me.

A descent of 1kft or so is enough to fill the battery to the brim, after which you have no electric brakes. I figure running the A/C on max would be a good way to burn up charge so as to keep your friction brakes cool. Maybe the car is smart enough to run the heat in such a situation.

If only you had some better instrumentation, or if I had a mountain to descend, we could find out exactly what's going on.

 

well, the ice ran on the way up the hill, and the coolant was still warm enought to provide sufficiently warm air with a little boost from the ice. what was the outside temp? what temp did you have the heat set at? how many miles is it to your friends house? i doubt the heater is much different, if at all.

 

The heat is from the engine block, coolant, etc. As you leech off the heat into cabin, coolant temp will drop. When it hits 110 deg F (?), ICE will come on.

 

As far as I can tell from schematics the heater is as normal as any ICE vehicle. Are you sure the engine never ran? The engine had to be running to circulate coolant through the heater coils if you got hot air from heater vents. If you were on recirculate and the outside air not cold enough the heater fan merely recirculated cabin air.
PS run that 'higher down the mountain' by me again.

 

Nope. Prius c has an electric water pump. The engine does not have to run for coolant to be circulated.

 

The engine would have had to run when you restarted the car for the trip home. It will run until the coolant temp is around 150F. If you had warm air, then you had warm coolant. If the engine didn't start then there was enough heat in the 150F coolant to keep the car warm for 18 miles.

 

Well if you drove 5000 feet up, that would certainly have warmed up the coolant (was it a 1 hour visit?) and then going downhill (5000 ft) assuming you needed to brake would likely have fully charged the HV battery which may then cause the engine to do compression braking (not sure if you were in B "gear". This air compression would cause engine to heat up which may explain how the coolant warmed up.

 

I can't believe this question hasn't been definitively answered yet. According to these posts, the Prius C has 3 electric heaters to supplement the ICE:

So which is it? ICE+Electric heating or just ICE?

If the OP was indeed correct in observing the ICE not running during his 18-mile downhill jaunt, that would lead one to believe there is supplemental heating element involved. But it also seems unlikely he could manage to keep the ICE from turning over for 18 miles going downhill..

 

3 X 30 Amp fuses =90 Amps X 12V = 1080 Watts. That would be quite a draw on the small 12 V battery. Possibly heating would only run while 12 V battery is getting a matching charge from the HV system. I've got to take a look to see if there are 30 Amp Heater fuses in my model and to take them out if there are.

 

I'm assuming the North American model very probably has the PTC heaters while the Australian one does not.

Just from reading this thread, it doesn't seem relevant here. The OP says: "the ICE came for just a bit just like it normally does". This means the ICE warmed the coolant to at least a reasonable operating temperature, which is going to be higher than anything you can set on the climate control. The minimum initial warmup in my C is to raise the coolant temperature to exactly 40°C (104°F). Normal operating temperature is more like 80-90°C (176-194°F). If the OP's coolant temperature had not fully cooled while they were at their friend's place, then the minimum length of time for the warm up cycle would have raised their coolant temperature to some point above the minimum I mentioned above.

I believe the engine should have very probably been plenty warm enough to provide cabin heat. It doesn't cool down that quickly unless the ambient temperature is really cold (like freezing point cold). As another poster mentioned, if the ICE really does cool down that much to some minimum threshold, I believe it should come again to raise the coolant temperature back to the minimum buffer point.

 

This is from the Gen II forums, but may still be helpful insight:

The ptc heater | PriusChat

 

i could never feel the ptc heaters in my '04 or '08, are the C's larger?

 

The heater only works when the car is in ready mode.

 

The PTC energizes if the engine temp is below 131F, the air temp is set to max hot, the air is directed to the floor or the windshield, and the blower is on. Running in ECO mode disables the PTC.

 

Thanks. I failed to check how the water pump was controlled so absolutely all the ECU has to do is turn the pump on and water circulates but where is the hot water to heat the heater coils? So is there an electric heater in the cooling system? (no I'm not where the schematics are).
Wonder if anyone has blocked off part of the radiator for inter let the engine run warmer easier. The thermostat should control 195F in any case but I wonder if the temperature is 'held' at 195F but with only trickle flw (floe past the 'closed' thermostat (which never really fully closes.

 

yes, there are many threads on grille blocking here.