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dacpdx

New Member
Sep 5, 2018
3
20
portland
so is there any way to turn of the heater? i can’t find one. if the temperature selected is just a little bit warmer than the cabin, i see the red tinted air graphic, which i assume means the heater is powered up. The ac can be switched off in manual mode, but i can find no such option to disable the heater. here in the pacific northwest in late summer and early autumn we often don’t need heating or cooling, would be nice to be able to shut this off instead of messing with the temperature setting.
 

gavine

Petrol Head turned EV Enthusiast
Apr 1, 2014
2,637
2,218
Philadelphia, PA
I started a thread, posing that same question 4 years ago in the 5-page discussion linked below:

Heater on/off Button?

just set the temperature lower than ambient with AC off.

But what if you want the AC on for humidity control but don't want the heater and AC running at the same time?
 

Eno Deb

Active Member
Aug 17, 2018
2,641
3,402
SF Bay Area
I think the best solution would be if we could set a window of acceptable temperatures in auto mode rather than just one exact temperature. For example, you could set it to "67-74", and the heater/AC would only turn on if the temperature is outside of this range. Most people don't care about the exact temperature, they just want it to be reasonably comfortable. Turning on the heater in summer because of a few degrees difference is just wasteful ...
 

RTPEV

Active Member
Mar 21, 2016
1,755
2,354
Durham, NC
Reading your thread now @gavine .

I was just about to say what @Eno Deb just said. Any time you have a thermostat controlled system that switches back and forth between cooling and heating, you need to design in a dead zone where it does neither, but just runs the fan for fresh air. Basically this takes me back to where we were in the early Nissan LEAF days. You could turn the A/C off with a button, but the only way you could disable the heat was to turn the temp down. Which means that during spring and fall when the mornings are cold but the afternoons are hot, you are constantly switching the temps. It's a real hassle. Eventually Nissan smartened up and gave us a "HEAT" button so we could disable the heater. With the LEAF we had to buy a whole new car to get this (or do a hack mod). Tesla would merely have to roll out new software. Having the driver/passenger zones only complicates this further, because my wife sets her side 4 degrees warmer than me, and I am constantly "sync"ing the temps so I can turn it down below ambient to avoid the heater, and then she has to un-sync and reset her temp when she gets in the passenger seat.
 

gavine

Petrol Head turned EV Enthusiast
Apr 1, 2014
2,637
2,218
Philadelphia, PA
At least on the S, if you turn off A/C in manual mode, this turns off both heat and cooling, and just leaves the fan on ... It may work the same way on the 3

Are you sure about this? I always turn the AC off in the winter and my heat works. Why would they require the AC to be on in order to have heat? That would be very confusing to customers.
 
Are you sure about this? I always turn the AC off in the winter and my heat works. Why would they require the AC to be on in order to have heat? That would be very confusing to customers.
I will double check. I know I've seen the same issue where my heater had come on when I didn't want it to be on, and turning off the A/C turned it off. After all, A/C stands for air conditioning and is technically not just limited to cooling...
 
so is there any way to turn of the heater? i can’t find one. if the temperature selected is just a little bit warmer than the cabin, i see the red tinted air graphic, which i assume means the heater is powered up. The ac can be switched off in manual mode, but i can find no such option to disable the heater. here in the pacific northwest in late summer and early autumn we often don’t need heating or cooling, would be nice to be able to shut this off instead of messing with the temperature setting.
We in Southern California never need the car seat heater. We just need an OPTION TO COMPLETELY DISABLE THE SEAT HEATER.
I've discovered today while fumbling with the screen, that inadvertently I touched the icon and the heater started to work (it is balmy 72 deg F here today).
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
15,928
20,708
Riverside Co. CA
We in Southern California never need the car seat heater. We just need an OPTION TO COMPLETELY DISABLE THE SEAT HEATER.
I've discovered today while fumbling with the screen, that inadvertently I touched the icon and the heater started to work (it is balmy 72 deg F here today).

Actually, yes we do in southern california need the seat heater, especially in THIS car. Its much more efficient to use the seat heater instead of the actual heater, so the most efficient way to use the system during the "winter" for us is to use the seat heater and turn down the temperature so that the actual heater does not come on.

I bought my Model 3P in december of last year, and used seat heating instead of the heater on most of my morning drives until spring.
 
In auto, the HVAC runs heat and AC over wide temperature ranges, particularly the AC at cooler temperatures to de-humidify. The only solution is to turn auto off, select a fan speed and a temperature. Select a temperature below the ambient to make sure heat is off. Turn re-circ off and use outside air to reduce window fogging. In colder temps try this method which keeps the AC off but turns the heat on. You still may have to periodically defog the windshield which turns on the AC. After that you have to start all over again turning off AC, etc.
 
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But what if you want the AC on for humidity control but don't want the heater and AC running at the same time?

I don't think that's possible.

Humidity is removed from the air when temperature drops as it passes through the evaporator core. This is why air conditioning is known to remove humidity, as it forces the dewpoint of the air down.

At this point you have air that is significantly colder than ambient. How would you warm and back up to ambient without using the heater?
 
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gavine

Petrol Head turned EV Enthusiast
Apr 1, 2014
2,637
2,218
Philadelphia, PA
I don't think that's possible.

Humidity is removed from the air when temperature drops as it passes through the evaporator core. This is why air conditioning is known to remove humidity, as it forces the dewpoint of the air down.

At this point you have air that is significantly colder than ambient. How would you warm and back up to ambient without using the heater?

If the AC compressor is running at its lowest level, it won't cool the air significantly, but will be enough to dehumidify the air still.
 
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