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

[Josie]

Car heater can be turned on when the engine coolant temperature reaches 80 to 90 degrees Celsius. The heat source comes from the engine coolant. Turning on the heater too early will slow down the warming of the coolant and prolong the warm-up time. The functions of car air conditioning are: 1. To cool, heat, ventilate and purify the air inside the car; 2. To provide a comfortable environment for passengers, reduce driver fatigue and improve driving safety. The maintenance methods for car air conditioning are: 1. Do not set the temperature too low when using it; 2. Control the direction of air vents; 3. Do not use it for too long; 4. Turn on high air volume appropriately; 5. Turn off the air conditioning when driving at low speeds.

[Faunus]

I've been driving this SUV for five years, and in winter, the most important thing I pay attention to is the water temperature gauge. When starting the engine, the needle barely moves, and the air coming out of the heater is cold at this point. I usually wait until the water temperature rises to around 50 degrees before turning on the first level of the heater—it's not very warm yet, but at least it's not freezing. The real hot air comes out when the water temperature reaches the middle of the dial, around 80-90 degrees. One thing to note is that keeping the heater on doesn’t harm the engine; in fact, it helps stabilize the water temperature since the heater utilizes waste heat from the engine. Before driving my kids to school in the morning, I warm up the car for about five minutes until the water temperature rises, ensuring the cabin is comfortably warm when we set off.

[DelDaniella]

From the principle of heat exchange, the warmth of the heater comes from the engine coolant. The coolant needs to reach its normal operating temperature (typically 85-90°C) to effectively transfer heat. Actual test data shows that when the water temperature is below 60°C, the outlet air temperature rarely exceeds 25°C. Some new cars come with a coolant temperature indicator light—once the blue light turns off, you can try turning on the heater. Additionally, using the heater during a cold start will prolong the engine warm-up time, so it's recommended to drive for about 2 kilometers before turning it on. A handy tip for northern car owners: when the windshield is icy, turning on the heater with external air circulation can defrost it faster than using a snow scraper.

[McTalia]

I'm used to checking the position of the gauge needle. When the needle is about 1/4 above the lowest mark (around 50°C), you can turn on the minimum fan speed, and the air will be warm. Once the needle reaches the middle mark of the gauge (around 90°C), you can get comfortable warm air. After turning on the heater, switch the circulation mode to internal recirculation to warm up faster. Remember, if the coolant temperature hasn't risen, turning on the heater won't be effective and will only increase fuel consumption (due to the blower's power usage). In winter, while waiting for the coolant to warm up after a cold start, you can turn on the seat heating function first.