Both the National Highway Traffic Safety Administration (NHTSA) in the U.S. and Transport Canada are investigating complaints from Tesla owners about heat pumps failing in cold conditions.

In recent weeks, a number of Tesla owners have taken to social media to reveal that their climate control systems have stopped working. It appears the issue is limited to Model 3 and Model Y vehicles which have dedicated heat pumps designed to reduce battery consumption during cold weather.

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One Tesla Model Y owner took to Twitter to reveal that the climate control stopped working in -40°C (-40°F) weather. Tesla Service was called but the technician was unable to fix the issue. The owner was particularly concerned for the welfare of his two kids under 3 that were in the EV.

Another Model Y owner who’s a member of the Tesla Model Y Canadian Group on Facebook says that his heat pump failed at -5°C (23°F) while on a skiing trip.

“I preheated for 30 minutes until the heat gave out and started blowing cold air,” he revealed. “Tried a reset, tried defrost and nothing. Wipers frozen to the windshield as well as ice forming. Wasn’t a safe drive home to say the least but thankfully not -20 or -30 like some of you out there across Canada. Service was booked for January 7th then rescheduled for January 25th. I don’t have heated steering so my fingers were frozen.”

Transport Canada recently opened an investigation into the issue after receiving 16 consumer complaints, Auto News reports.

iPhoneInCanada adds that Tesla’s support team acknowledged the heating issue a couple of weeks ago, revealing to owners that a firmware issue may prevent the heating from working in cold weather. It suggests pre-conditioning vehicles for at least 30 to 60 minutes before departure and reported that a firmware update is in the works.