修車 car

TELSA MODEL 3 2019/2020 (no heat pump ) 

冷氣吹大概20分鐘後因為過冷 蒸發箱結冰無法出風 外面壓縮機低壓管結冰 查詢車內電腦看蒸發箱溫度異常 應該要接近0度 但是卻顯示50度 所以判斷感測器異常

Problem:

Initially, the AC works fine and blows very cold air. After a period, say 20 minutes, the AC airflow diminishes and eventually stops completely. Upon inspection in the engine bay, the low-pressure metal pipe of the AC unit freezes over. During this time, the compressor doesn't stop; it runs continuously, which can be confirmed by the sound of its operation. No error code observed in service mode.,

Temporary Solution: Stop using the AC (turn off the AC, or switch to manual control and turn AC off, and set the fan to high). Once the frozen metal pipe thaws (presumably at the same time as the ice on the AC evaporator melts), the airflow returns to normal. At this point, turning the AC back on results in very cold air and strong airflow. However, after a few minutes, the airflow stops completely again due to the low-pressure metal pipe and evaporator freezing.

Checks: I checked the two green temperature sensors (HVAC - THERMISTOR DUCT 1500650-00-A) on the left and right air vents above the AC evaporator housing. In service mode, their temperatures appear normal. The cabin temperature sensor (the one directly below the panel) also seems normal, as observed via the Tesla App's cabin temperature reading. 

The white temperature sensor (HVAC THERMISTOR EVAPORATOR) 1500645-00-A, located below the driver's seat near the AC evaporator housing, its temperature-resistance relationship measured. It showed approximately 2 kΩ at room temperature (30 °C) and around 8 kΩ near 5 °C. Its behavior seems normal, but I suspect this sensor is faulty (random failure). This part is designed to prevent the compressor from operating at excessively low temperatures. When the AC is running continuously (compressor operating), if I directly unplug this white thermistor (HVAC-THERMISTOR EVAPORATOR), the compressor immediately stops. Service mode also detects that the sensor is disconnected with error code VCRIGHT _a144_evaporatorTempSns.

Conjecture: It's likely that this white temperature sensor, the HVAC-THERMISTOR EVAPORATOR, has an issue with its low-temperature detection. This prevents it from transmitting a sufficiently low temperature reading to shut off the compressor, even when the compressor's operating temperature and the low-pressure copper pipe are excessively cold and freezing. 

Reference [1] https://teslamotorsclub.com/tmc/threads/2019-no-heat-pump-model-3-ac-no-air-freezing-of-the-ac-compressors-low-pressure-pipe.345173/

I use ScanMyTesla to read my car's HVAC data. "Evap temp" is always at a very high temperature, 55-65 °C, even though the AC has been on for a while and the airflow is very cold. This further confirms my suspicion. This symptom is very similar to @Ken43's case.  

This problem got fixed after replaced the temperature sensors. By the way, just buy GM part #13276269 or compatible, it is much cheaper and works well.