Why is the car heating up slowly?

[DiGemma]

Reasons for slow car heating: 1. Excessive scale on the coolant temperature sensor: This reduces the sensitivity of the coolant temperature sensor, leading to slower temperature rise; 2. Fault in the radiator fan circuit system: This causes the engine to remain in forced cooling mode for extended periods, resulting in rapid coolant temperature drop; 3. Missing or damaged thermostat: The thermostat controls the direction of antifreeze flow, regulating the major and minor circulation loops. Without a thermostat or when the thermostat valve fails to close properly, the coolant continuously circulates in the major loop, causing the engine coolant temperature to drop faster and resulting in slower engine temperature rise.