2021 Model 3 Heater blowing cold air

[Big Dog]

You're doing it wrong.

you're better off putting a lower air temp, and using seat heaters. Also having fan on 1 means the car isn't moving much air around the cabin, which means it has to run the heater more to maintain that temp.

Exactly. To save electrons, seat heaters with a lower cabin temp, and Auto for fan. (Also helps keep the windows from fogging up.)

 

[JCtx]

On 2021 cars, seat heaters probably consume more electricity than heating the cabin at 72F with fan speed at #1 (manual mode), with the more efficient heat-pump, no? I'd be more preoccupied with reducing wear and tear on the heat-pump, to prevent future issues, than saving a bit of range, but both help, I guess.

And finally, is it better to leave HVAC in heat with fan speed at #1 @ 72F, or raise the temp and fan speed for a while, then shut off HVAC for an additional while? I was under the impression the former is the better way, but let's see what's the consensus . I say that because the batteries will be generating heat at 80+ mph constantly, and if you only have fan speed at #1, the pump shouldn't have to work at all, providing the heat from the battery pack.

 

[DDHEverything]

People who don’t use heat when it’s cold out to save a few miles aren’t fun at parties.

 

[dmurphy]

I'd be more preoccupied with reducing wear and tear on the heat-pump, to prevent future issues, than saving a bit of range, but both help, I guess.

It’s a car, not a Ming vase. Drive it, be comfortable, enjoy it. Mostly in that order. LOL.

 

[Gasaraki]

I have had my 2021 model 3 for a few weeks and one day the heat wasn't working. It was about 40F out and not much warmer in the car and it was blowing cold air. I tried switching the hvac on and off and that didn't help. I then turned the heat up to max and heard a sound that I believe was the the heat pump kick on and then started getting hot air pretty quickly. I then turned it back down to my target temp and back to auto and the hot air kept coming out. Only time I have had this issue so haven't been able to test if it works at other points but maybe a sensor issue or something and kicking the heat up high enough fixes it??

People need to understand how heat pumps work. When ice forms on the outside coils, the heat pump needs to run in reverse melt the ice. During that time it will blow cold air and no matter if you shut it off and start it again it will continue to do that till the ice has melted. I have a heat pump for my house and it does this.

I don't know know if it's the exact same scenario but this does happen with heat pumps.

 

[run-the-joules]

On 2021 cars, seat heaters probably consume more electricity than heating the cabin at 72F with fan speed at #1 (manual mode), with the more efficient heat pump, no?.

Warming the occupants, or heating the cabin?

 

[leonar40]

People need to understand how heat pumps work. When ice forms on the outside coils, the heat pump needs to run in reverse melt the ice. During that time it will blow cold air and no matter if you shut it off and start it again it will continue to do that till the ice has melted. I have a heat pump for my house and it does this

The defrost part is correct, but the heat pump should not blow cold air during that time. It should be supplemented by whatever AUX heat source it has. In the new cars I assume that's electric. In your house that could be electric, gas, geo, etc.

When my home heat pump goes into defrost mode, the temp at the register actually goes UP because it engages the AUX electric heat during the defrost period.

 

[Cleo-n-Company]

On 2021 cars, seat heaters probably consume more electricity than heating the cabin at 72F with fan speed at #1 (manual mode), with the more efficient heat-pump, no? I'd be more preoccupied with reducing wear and tear on the heat-pump, to prevent future issues, than saving a bit of range, but both help, I guess.

And finally, is it better to leave HVAC in heat with fan speed at #1 @ 72F, or raise the temp and fan speed for a while, then shut off HVAC for an additional while? I was under the impression the former is the better way, but let's see what's the consensus . I say that because the batteries will be generating heat at 80+ mph constantly, and if you only have fan speed at #1, the pump shouldn't have to work at all, providing the heat from the battery pack.

No one should have to be concerned about wear-and-tear on Tesla heat pumps and other HVAC components.

My 2005 Lexus RX blows cold when it needs to... blows hot when it needs to. It's been doing this for 15 summers and winters without a hitch.

I sometimes see other Tesla drivers with their windows down on our Sacramento 105-degree summer days. Bewlidering range-extending behavior - at least in my book...

 

[Cleo-n-Company]

People need to understand how heat pumps work. When ice forms on the outside coils, the heat pump needs to run in reverse melt the ice. During that time it will blow cold air and no matter if you shut it off and start it again it will continue to do that till the ice has melted. I have a heat pump for my house and it does this.

I don't know know if it's the exact same scenario but this does happen with heat pumps.

I'm assuming there has to be some kind of heating coil or other device to work with the heat pump when it's Syracuse NY cold. I can't believe a carmaker would create a heat pump that doesn't have the "oomph" when you need it -- below 32F etc.

 

[variable]

Didn't Bjorn just do a video showing that at least in very cold weather, it's not really worth the energy savings to not run the heater? There's extra energy usage, but with the heat pump it seems that the saved energy wasn't really worth the freezing cold and didn't have a huge impact on the efficiency.

I think unless it's an emergency and you absolutely need to count those miles to reach the next charge, it's not really worth it. ICE cars lose efficiency running HVAC as well.

 

[DDHEverything]

Didn't Bjorn just do a video showing that at least in very cold weather, it's not really worth the energy savings to not run the heater? There's extra energy usage, but with the heat pump it seems that the saved energy wasn't really worth the freezing cold and didn't have a huge impact on the efficiency.

I think unless it's an emergency and you absolutely need to count those miles to reach the next charge, it's not really worth it. ICE cars lose efficiency running HVAC as well.

Military never worth the freezing cold or burning hot. Plan properly and drive in comfort.

 

[Whitehawk]

It’s a car, not a Ming vase. Drive it, be comfortable, enjoy it. Mostly in that order. LOL.

Amen - amazed that some people treat their cars like museum pieces. Parts wear out...that’s why we have warranties and replace them when they fall apart. The value of the heat pump is range...something my 2018 M3AWD has too little of because of resistance heat. I refuse to be uncomfortable while I drive...

 

[dmurphy]

Amen - amazed that some people treat their cars like museum pieces. Parts wear out...that’s why we have warranties and replace them when they fall apart. The value of the heat pump is range...something my 2018 M3AWD has too little of because of resistance heat. I refuse to be uncomfortable while I drive...

Well, to be honest -- I don't like to go very far when it's brutally cold out. My 2019 LR AWD can do 200+ miles in the dead of winter pretty easily, and the entire state of NJ is 170 miles from north to south.... so I'm more than happy. And I agree - I flat-out refuse to be uncomfortable when driving. To heck with that!

 

[JCtx]

I meant the best way to use the heat pump... WHILE being comfortable. I was just curious if it was better to run it all the time in low, or high for a period, then shut it off. And also in case of a 'range emergency'. But most of the time will leave HVAC on all the time it's needed. And once cabin is toasty, you can maintain it with fan in #1 speed (the lowest). Also leave seat heaters off once warm (which take a few minutes), since they suck a lot of energy. Plus they usually shut off automatically anyway. Going on our first long trip on Thursday, so we'll have a chance to test the car in every condition. We'll leave around 32F, so will have to run heat most of the first leg at least, which will be 135. Will top off to 95%, since I plan to hit 80+ most of those miles. Wish me luck . But as long as the car doesn't leave us stranded, will consider it a success. He he.

 

[Gasaraki]

The defrost part is correct, but the heat pump should not blow cold air during that time. It should be supplemented by whatever AUX heat source it has. In the new cars I assume that's electric. In your house that could be electric, gas, geo, etc.

When my home heat pump goes into defrost mode, the temp at the register actually goes UP because it engages the AUX electric heat during the defrost period.

No unfortunately it doesn't do that in my house but it's minor issue. I have a gas furnace as my AUX heat. In a Tesla, they don't have the resistive heater anymore so it doesn't have an AUX heat.

 

[Gasaraki]

I'm assuming there has to be some kind of heating coil or other device to work with the heat pump when it's Syracuse NY cold. I can't believe a carmaker would create a heat pump that doesn't have the "oomph" when you need it -- below 32F etc.

Think about it, Elon's motto is “The best part is no part. The best process is no process.” When they added the heat pump, they removed the old heater. The only AUX heating is by running the motor inefficiently, which they do anyway to heat the batteries, etc.

 

[dmurphy]

Think about it, Elon's motto is “The best part is no part. The best process is no process.” When they added the heat pump, they removed the old heater. They only AUX heating is by running the motor inefficiently, which they do anyway to heat the batteries, etc.

Right. This is why I was a bit concerned with the heat pump configuration; it’s probably fantastic 95% of the year. But those really cold, 0F or below days ... I know Tesla’s got some of the best engineers in the world, but that heat pump is going to struggle. They’re good, but still haven’t beat physics.

 

[Big Earl]

People need to understand how heat pumps work. When ice forms on the outside coils, the heat pump needs to run in reverse melt the ice. During that time it will blow cold air and no matter if you shut it off and start it again it will continue to do that till the ice has melted. I have a heat pump for my house and it does this.

I don't know know if it's the exact same scenario but this does happen with heat pumps.

That’s what happens in air source heat pumps with an external refrigerant heat exchanger. Tesla uses no such refrigerant heat exchanger and thus, does not have to do defrost cycles to rid itself of ice. Yes, the system can scavenge heat from the outside air, but not in the conventional manner you’re referring to.

Here is an excellent three-part system on the Tesla heat pump. It details all of the system’s modes (12 heating modes and 3 cooling modes) and clearly explains how this isn’t a conventional heat pump HVAC system.

 

[vickh]

i was really excited about the heat pump. All these posts are making me glad i went with a used model instead with the regular heat.

opposite problem with rear AC blowing hot air in 2019 . Service said they'd fix with update

 

[Acxxu]

I have a 836xxx VIN Tesla Model 3 Performance ("MY2021") here up in the very north, way beyond the Arctic Circle.

No problems for the first 1,000+ kilometers (even have slept in the car) until I now ran into this issue yesterday when it was up to -39.5'C degrees (that's -39.1 Fahrenheit) outside on a ca. 40 km (25 mile) drive times two (back and forth) in the middle of nowhere practically. Luckily I was prepared for normal reasons per the extreme weather, having e.g. three pairs of pants, three pairs of socks and such as heat pads (those that bring you 4 hours of warmth when opened), etc. you get the idea.

The car had heated up normally before departure, operated from the mobile app ("turn on heating"); but during the drive, no heat was coming from the vents, only seat warmers were working (luckily they worked well).

Before driving back from my chores, I tried yoyoing the car to get some heat into the battery-- this helped to get some warmth out from the aircon, but just barely and only for a short while. So, I had to drive back without any other heat source from the car than the seat heating. My mobile app recorded around -13'C (8.6 Fahrenheit) in the cabin as I was back at the homebase. At this point, I re-connected the Tesla to the Wall Charger. Not sure what helped, but at this point as it started charging, the mobile app showed that it is heating up the battery as well - the app was able to heat up the car all the way to +24'C and beyond.

I went on a short drive and could leave the heater "ON" while visiting the store to pick up groceries. Coming back to the car it was nice and warm and fully functional.

This morning, I have same issue again. I turned heating on from mobile app before departure and it "seemed to work", but after some time I saw from the app that the car wasn't getting heat (and the screen view was presented like it was actually off). Re-trying to turn heating on from mobile app reports "Failed to turn on climate" or "Failed to turn on max defrost", depending which functionality you try under Climate - unless I am sitting in the car or have the car door open. Behind the rotor-icon it says "Climate keeper unavailable due to system fault" beneath the OFF/ON/DOG/CAMP.

I've tried just about everything (phone shutdown, opening/closing car with keycard, steering-wheel button resets, yoyoing - stators get warm but doesn't get distributed in cabin, tried connecting back to TWC getting battery heat icon back light up, it did but I'm not able to get interior to warm up..), but it seems that I can't get the car's interior warm up.

I take it from this discussion that there are some known sensor issues, but the most peculiar thing was that I got it working yesterday by chance so I'm sort of wondering that is there a software related issue at play too.

Any suggestions?

Btw, might just be a coincidence, but as this is a new car; this started happening just after I had connected my phone as "Phone key" for the car.. The closest Tesla Service Center is conveniently about 1,000 kilometers away. Car is drivable and operational otherwise, but it's still -26'C outside (-14.8 Fahrenheit) so not optimal to "just drive" in the cold.