I normally run my Prime with the fan off so the heater and AC are off. I noticed that when running in EV mode with the fan off if the temp is set* to a warm setting (70+ degrees F) I can feel warm air coming from the vents when the car is moving. Where is the heat coming from? I understand that in HV mode it could supply passive heat through the radiator or exhaust heat. Maybe in EV mode it supplies passive heat from a cooler for the electric motors or hybrid system? *With the fan off you can’t adjust the cabin temp. By “set” I mean: turn the fan on, set the cabin temp to 70+, then turn the fan off. That temp setting stays in memory until you manually change it.
if you turn the temp to low, does the air cool down? what is the outside temp? older pri had electric preheaters
Interesting observation. I have never checked the vent to feel the warm air coming out, but I do drive my PP with the fan off most of the time. As you noted, when the fan is set to off, HVAC is OFF, and the PP's A/C ratio on the Eco Diary stays 0%. The question is by "feel warm air" what exactly is the air temp in the cabin and outside of the car at the air intake. It may be that the ambient air outside is slightly warmer than the cabin temp?
Yes, the vent air temperature goes down when the temp is set on lower settings. I have never noticed that it is colder than the outside temp (no passive AC). Outside temp is 55-65F.
No, the vent air is noticeably warmer than the ambient cabin or outside temperature. Try it with the temp set to maximum with the fan off. It might happen only while driving because while stationary there is no air movement through the vents.
I will have to see what I can feel out of the vent. If your outside ambient temp was 55-65F and you are noticing warmer air coming out of the vent, then this passive heat must be substantially warmer than 70F. As I said, I have never checked the vent on my PP while the HVAC fan is set to OFF, but if ~70F or higher temp air is coming out passively, then I am sure I would have noticed it by now. I usually keep my HVAC OFF even when the ambient temp is well below 32F. In fact, I don't usually use heat unless the ambient temp is lower than 20F, but I have never noticed ~70F or higher temp air coming out of the vent in my car.
Maybe it is just me but the HVAC is considerably loud and noticeable when it is turned on. Specifically when stationary and no ambient noise around. Even over the whole pedestrian noise maker.
I've observed something similar. It's a mystery to me, too because when I stop I don't hear the heat pump running.
I've never worked on a Prime, but that would sure be very Prime-specific if it did; nothing like that happens in Gen 1, 2, or 3.
OK, I run my weekly errand today and drove ~40miles in my PP. I did all 40miles with the HVAC fan set to off position. I was only able to drive on EV mode for the first 25miles or so. During that time, I tried feeling the vent. Absolutely no warm air coming out of the vent. If anything, it felt cooler but I think it is just because of the drift. BTW, the ambient temp was 28F cloudy with some mixed precipitation. When I run out of EV range and switched to HV, even though I did not turn on the HVAC, there was definitely warmer air coming out of the vent.
I know, I’ve tried it a few times recently and got no heat using EV. But I’m sure it has happened a few times when leaving my garage in the morning on cool SoCal mornings (we had frost not too long ago). And the air was definitely warm. I’ll continue to test it. I also tried it recently using HV and definitely had passive warm air.
I think I was using the seat heater with the fan off. And I noticed the vent air was warm. I’ll try that again.
My observation is similar. Another thing is if you set fan off, air coming from outside, then you pull down the window a bit, you can fell the vent air blow a bit stronger vs when the window close.
