Why does my Kia Stonic engine temperature rise when the AC is on in city traffic during hot summer days?

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Why does my Kia Stonic engine temperature rise when the AC is on in city traffic during hot summer days?

In Pakistani cities like Lahore o r Karachi, where summer temperatures exceed 40°C, my Kia Stonics temperature gauge often rises when I’m stuck in traffic with the AC running. Once I start moving again, the temperature s. Is this a sign of a weak radiator fan, thermostat problem, o r just normal behavior in extreme heat? Do other Pakistani owners face this too, and what’s the most common fix?

Talha Kyanii asked on 20 Sep 2025 16:59:03 pm

1 Answer

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Gari Master - on 20 Sep 2025 17:00:30 pm

Likely Causes in Pakistan:

Radiator fan not engaging properly — In traffic, your car relies on the radiator fan to cool the engine. If the fan motor, relay, o r temperature sensor is faulty o r weak, heat builds up fast when the AC is running.

Overworked AC system — The condenser in front of the radiator gets hot with AC use, which adds heat load to the radiator. If airflow is low no movement + dirty fins, overheating can happen.

Clogged radiator fins — Dust, bugs, and smog particles in Pakistani cities reduce airflow efficiency through the radiator and condenser.

Old o r diluted coolant — If youre using tap water o r expired coolant, the boiling point s, and cooling efficiency suffers.

What Most Owners Do:

Clean the radiator and AC condenser fins with pressure air o r water.

Check that the radiator fan turns on automatically when engine heats up o r AC is on.

Replace coolant with a high-boiling-point, pre-mixed coolant — not tap water o r home-mixed.

Inspect o r replace the thermostat if it opens too late.