To use the car's battery to produce heat directly would flatten the battery in double quick time so the car draws in heat from outside the vehicle using a heat pump. That works a lot of the time but when the temperaure outside is very low, the heat pump has to work hard to grab heat and can overload and fail when trying to do so. Electric cars are just not suited to the very cold environments often experienced in Northern North America.
Tesla owners living in Alaska and western Canada are being forced to drive their vehicles without heat in the cabin when temperatures are dropping far below freezing.
The issue, which has plagued Model 3 and Model Y vehicles since last winter, started when a new heat pump system was added to the vehicles and persisted with a software update.
Tesla owners have taken to Twitter to share this frustration, as Elon Musk is the only person on the company's customer service team, with one customer saying his family could have been killed.
Tyler Selvig explained in a tweet that the heat stopped working in his Model Y while temperatures had dropped to -40F.
'Our Model Y could have killed my family today when the heat stopped working in -40c Called service and the reset and auto didn't fix. Hour away from any service,' reads the tweet.
Musk, however, has acknowledged the issue on Twitter, saying fixing this issue was a 'high priority' at Tesla, and this weekend, he announced that the automaker is rolling out a software fix for it: 'Firmware fix to recalibrate heat pump expansion valve is rolling out now,' He posted.
However, some Tesla owners shared images of their vehicle's heat pump, which appears to be damaged or is just not working.
This suggested a simple over-the-air update may not fix the problem.
'Heat pumps are not designed for areas that get under 20F… the colder it gets there, the longer/more difficult it gets to draw heat. Add in wind and ice, and things really just don't work,' the tweeted.
Wick H continued to explain that refrigerant is unable to be transfer heat at such low temperatures.
Several customers plagued by the issue opted to have their vehicle serviced instead of waiting around for an update from Tesla.
Twitter user 'Tapic' tweeted directedly at Musk saying: 'Are you going to comment on the fact that my Tesla is completely useless right now. My heat pump not working at -20c and the next service date is Jan 28. Is this acceptable? Seems to be a common issue. FIX IT!'
The National Highway Traffic Safety Administration (NHTSA) and Transport Canada have also opened investigations into the defected heating system over 'potential safety concerns.'
NHTSA said it 'is aware of the issue and is continuing to gather information, discuss the issue with Tesla and evaluate potential safety concerns.'
And according to Transport Canada, the issue 'may affect windshield defogging/defrosting and therefore driver visibility.'