1. Any water in your radiator?
2. Any leak from water hoses around the engine?
3. Water lost from radiator?
4. Engine temperature with Aircond switch off, but climbs when A/C switch during idling at traffic lights or traffic jam, BUT temp back to normal under normal driving?
5. Is the thermostat functioning?
6. When engine hot, does radiator cold (no water flow)?
7. Any leak at water pump?
8. Have u done air bleeding?
9. Have u flush your radiator lately (maybe once or twice a year)?
10.Have u used coolant to lower the water temp, and prevent rust/sludge in the cooling system, and lubricate the water pump?
11.Is the engine fan running fast enough, is clutch OK?