It was reported on January 15 that many owners of Tesla Model 3/Y had previously complained that Tesla had a problem with a heat pump resting in a low-temperature environment, and the vehicle could not be heated by a heat pump in an extremely cold environment. Some 2020-2021 Model 3s and Model Ys still have issues, despite Tesla’s previous updates with defective sensors.
The problem occurred because the heat pump air intake froze, causing abnormal sensor data and shutting down the entire system. According to reports, Tesla today pushed the 2021.44.30.7 OTA update for the vehicle to solve this problem. The changelog states that this version of the system allows the heat pump to start smoothly at lower temperatures. Users can turn on the heating function of the vehicle through the mobile app 30-60 minutes before departure to warm up.
However, this update also has a problem that leaves hidden dangers. If it is in an environment of -15°C, the heat pump heating may still fail. Tesla is advising owners to park their cars in as warm a place as possible to warm up the vehicle to address this issue. In fact, after canceling the PTC heating and heating, only the heat pump is used for heating, and Tesla’s poor heating efficiency in a low-temperature environment is also a sure thing. This is determined by the working principle of the heat pump.
According to reports, the main components of the heat pump are 1: condenser (heat release), 2: throttle valve (decompression), 3: low temperature (heat absorption), 4: compressor (pressurization). In the above process, the low-boiling liquid (such as Freon in the air conditioner) evaporates after being decompressed by the throttle valve, absorbs heat from a lower temperature (such as outdoors), and then compresses the vapor by the compressor to increase the temperature.
After passing through the condenser, the absorbed heat is released and liquefied, and then returned to the throttle valve. This cycle of work can continuously transfer heat from the cooler to the higher (requiring heat). It can be said that PTC converts electrical energy into heat energy and produces heat. In extreme cases, it can only achieve 100% energy conversion. Consuming 1 joule of energy can only provide a maximum of 1 joule of heat.
The heat pump, which transports heat, can use 1 joule of energy to move more than 1 joule of energy from a colder place, so the power consumption should be greatly saved. However, in a low temperature environment, the external heat is low, and it is difficult for the heat pump to carry heat. When the outdoor environment is close to -18 °C, it consumes 1 joule of energy, and it can only carry about 1 joule of heat.
In addition, when the heat pump draws heat from the cold outdoor air, the moisture in the air condenses and freezes on the outdoor exchanger, and the system must remove this frost in stages. At the same time, when the air outside is extremely cold, the heat pump heating may not be as good as the PTC heating, or the heat pump system may not start. Therefore, the fact that Tesla is only equipped with a heat pump system for vehicles in the cold northern regions is worthy of scrutiny.