[JWardell]

I want to point out that ICE cars do not have heaters at all.
They simply redirect some of the heat they are already belching out into the neighborhood in the the cabin. Most ICE HVAC systems are nothing but a bunch of plastic diverter flaps. Remember the good ol' days when we had metal leavers that took some effort to switch modes and temperature? They were mechanically connected to those flaps.

However I DO wish we had some way to set a range of temperatures to keep the heat and AC off. I will set temp to 68 for heat and 72 for AC, and it is super annoying when it is within that range outside and I have to keep changing it. Or just turn it off and roll down the windows I guess.

Would also be nice if we had a heat pump for light heating use.

 

[JWardell]

This is the correct solution.

Also, why does everyone "overthink" the car temp? Day car is delivered, turn on auto, set temp, done. Never think of it again.

Agreed. I've had to untrained myself a bit. For years I would only enable AC in temps over 90+, because it would waste gas. The AC compressor in the Tesla is variable and uses barely any power especially when it isn't working hard. It took a while, but I pretty much just leave it now.

 

[JWardell]

Then again you live in Boston.
Here in DFW it is normal for my consumption to increase from ~250 to ~275 or 280 when I add A/C.
I do like the auto mode for A/C though. It seems to work well.

Exactly, in the 200's no big deal. When you get to the 400's because it's colder than Hoth outside, you realize the AC is not worth stressing about.

 

[JWardell]

Even an indicator that the resistive heater is energized would help.

The original firmware for Model 3 showed the blowing air color as red when heat was on. I could just tap the temp lower a couple of clicks and it would turn white indicating no wasted energy.

I would suggest they make the temp display (numerals) show red to indicate status of the resistive heater.

Except the status is very variable. Precomdition with heat while plugged in at home and watch it use 5+ kW in the first minute then quickly from to 2 to 3 then 1 once it is at temp.
Actually, the power meter under the speedometer will show power used by the heater, if you notice a few pixels are used when you are not driving.
I really wish I could make my gauges easy enough for everyone to use so you could make your own indicators for whatever you want.

 

[JWardell]

I like the list, but I think it should be enabled in options as extra stuff is confusing, and I also agree with Tesla's goal of keeping the car and the GUI as simple as possible.

So the wiring for the heater is accessible behind the RH console trim panel....

Please don't mess with that. It is high voltage and will kill you.
Serious.

 

[JWardell]

Antifreeze is poison too and so is brake fluid come to think of it.
Obviously you should always be careful and know what you are doing.

Better idea
MPP "disabled" some of the driving nannies with programming and a box. Could the same thing be done with the heat?

They are if you drink a large amount, but they can't kill you instantly if you so much as touch it.
I'm not thrilled there are HV cables right in the footwell, and thin so they seem less intimidating than the big ones in the back. You may be smart enough not to cut into them, but someone randomly reading your post may not be, so I just wanted to add the disclaimer.
If you want heat off just set temp to Lo and turn off AC.

 

[JWardell]

I finally bit the bullet and pulled the CAN connector to the cabin heater in my M3. My wh/m has dropped 5% the past 1000 miles with most of my driving on the freeway at 75-80mph.
Before I pulled the plug I was doing the whole routine to disable AC and set temp to LO and then turning it back on, etc so I should not have been using the heater at all ... Or so I thought.
It appears the heater is run all the time even when you are trying to cool the car.
The AC now cools the car super fast and actually too good. If it's 85 outside and I have the temp set to 81 the car cabin still gets down to 68!!
This is not a trivial amount of juice that appears to be straight wasted.
I really think the 2 temp setpoints is by far the best solution to extend your cars range and keep you comfortable within a larger temp range rather than just having 1 temp setpoint for the heater and ac to battle to keep. Until the 2 temp setpoint option is availiable a heater off button would be an amazing quick fix.
Will put a video showing how to do it hopefully this weekend.

Interesting if true. Maybe it is used to dry out the air and reduce condensation. But I don't think measuring your driving usage tiny improvement is really proof, a number of factors can make that 5% difference. We can defnieitly read power used by the HVAC though so I will have to look back through my warmer logs to see if any power is ever going to the heater.
Too late to do now, of course, now that it's in the 30s...very brave time of year to unplug the heater

 

[JWardell]

Just did a quick test with my dc amp meter clamp on one of the power cables to the cabin heater after reconnecting the CAN connector to the cabin heater after a failed software update which later worked after I reconnected the CAN connector.
Anyways It was only 72 outside with a cabin temp of 73 according to the app and I set the temp to 71 with recirculate on in manual mode.
No current showed on the meter until the inside temp went to my set point of 71.
Then the current started bouncing between .50 and .60 amps continuously, seemed to stick around .57 amps. That's about 200 watts at 350V... not chump change as far as wasted power in my electric car.
So leaving the AC on def uses the heater when it's hotter outside the car. Thats about 15 100watt equivalent LED bulbs I accidentally left on while running my car off a battery.

This doesn't take into account the extra power draw from the AC running all the time while fighting the heater.

I'm not sure a clamp meter will get a reliable reading if any if the wires are shielded, as they hopefully are being high voltage and needing the extra layer of safety. I do think we can read CAN data though. I did some specific tests with heat off and on, I will have to go through them to see if I can find actual heat currents.
You can easily do with with no tools though, by looking at the current when plugged in but not charging...the car will draw the same power from the wall as it is sending to the heater.
The heater will draw about 8000 watts (20+ amps) when cold and under full power, though I do believe it is fully variable.

 

[JWardell]

Well, here's the proof in the pudding! Here's a drive I made on a warmish day in September, and you can see I start with HVAC on, and you see ~1000W of heat used while just keeping the cabin around its set point of 21C. I turn off HVAC and you see the compressor and heaters turn off. I open the window and you can see the interior temp start rising. Halfway through I turn the HVAC back on and soon after the heat starts ramping back up as the cabin is cooled.
Then you see that huge spike at the end...I purposely cranked the heat to Hi and fan to max, and you see it ramp to 3350W per side...6700W total.
I'll add these to my DBC file so others can do their own sleuthing.