Do You Need to Turn on AC When Using the Car Heater in Winter?

[DiBrody]

You do not need to turn on the AC when using the car heater in winter. Using the heater in cold winter: To activate the heater, simply adjust the fan speed button to blow warm air. However, many people mistakenly turn on the A/C switch when using the heater, which may lead to increased fuel consumption or higher engine coolant temperature. A/C stands for Air-conditioning, and the A/C button controls whether the compressor operates. Inside the compressor, there is an electromagnetically controlled clutch. When the coil is energized, the electromagnetic clutch engages, and the compressor works. Otherwise, the compressor's pulley simply spins without the compressor functioning. Keeping it on continuously at high engine speeds may cause the coolant temperature to rise if heat dissipation is poor. Turning on the AC activates the cooling system: The main component of this system is the compressor. For the compressor to function properly, the ambient temperature switch must be closed. In winter, the ambient temperature switch cannot close, so power cannot be supplied to the compressor. As a result, the compressor does not work, and the cooling system remains inactive, with only the heating system operating. In fact, the heater utilizes the car's internal heat cycle and does not require the compressor to be activated. To use the heater, simply adjust the air conditioning buttons without turning on the AC switch. However, even if the A/C switch is turned on, it generally does not harm the engine—it might just consume a bit more fuel.

[DiMakayla]

Years of winter driving experience have taught me this: You actually don't need to turn on the AC for heating - the car's heating system uses engine heat directly, and running the AC just wastes fuel. However, when your windshield fogs up, activating the AC quickly dehumidifies and clears the fog, dramatically improving visibility and safety. My method: Turn on AC for 30-60 seconds when fog appears, then shut it off to save fuel. My routine is keeping temperature high with heat-only mode (AC off), only engaging AC when defogging is needed. This balances efficiency and effectiveness - practice makes perfect. Remember: Safety first! Fogged windows cause accidents, so address it promptly. That's the golden rule.