At what engine temperature can the car's heater be turned on?

[DelLuke]

Engine coolant temperature reaching 90 degrees allows for heater activation. Below are temperature range explanations: 1. Only when the engine reaches 90 degrees will turning on the heater not increase fuel consumption, though the heater can be activated when coolant temperature reaches approximately 40-50 degrees. 2. For models without digital coolant temperature displays, observe the analog gauge's needle position - different vehicles have varying gauge designs, so identify when warm air begins blowing. 3. Generally not recommended to activate the heater below 50 degrees, as the system will blow cold air in low-temperature conditions.