What are the symptoms of a faulty thermostat switch?
2 Answers
The symptom of a faulty thermostat switch is that the water temperature warning light stays on. The solutions are as follows: 1. When the coolant reaches the set temperature and the electric fan should start, the electric fan does not work. Even when the engine coolant has not reached the set temperature and the electric fan should not start, the fan turns on and continues to run until the battery is drained. 2. Due to the lack of cooling for the high-temperature engine coolant, the water temperature will continue to rise. When it reaches a certain temperature, it can cause engine cylinder scuffing, cylinder head deformation, and eventually lead to the engine automatically shutting down and failing to restart. Therefore, while driving, it is important to monitor the water temperature. If any issues are detected, they should be promptly inspected and repaired to avoid unnecessary repair costs.
Last time the thermostat switch in my car failed, the most obvious symptom was the AC completely malfunctioning—it blasted cold air when set to high temperature, but blew hot air when turned to low, while the fan intermittently turned on and off, causing wild temperature fluctuations inside the cabin like a rollercoaster. I also noticed severely reduced cooling performance, especially during long drives when engine bay heat increased fuel consumption dramatically, and the AC warning light popped up on the dashboard. Worse yet, sometimes the fan would inexplicably run at full speed, creating an unbearably loud noise, indicating possible circuit shorting or temperature sensor failure. Ignoring it makes driving in extreme summer heat or winter cold both miserable and hazardous. I recommend first checking fuses and connectors, but it’s best to get it repaired promptly to prevent minor issues from escalating into major repairs.
