If the radiator fan on your Pulsar NS200 is not turning on, even when the engine is hot, there could be a few possible causes for this issue. Here are some things you can check:
Fuse: Start by checking the fuse related to the radiator fan. A blown fuse could prevent the fan from receiving power. Locate the fuse box, usually located near the battery or under the seat, and check if the fuse related to the fan is intact. If the fuse is blown, replace it with a new one of the correct rating.
Fan Relay: The fan relay is responsible for controlling the power supply to the radiator fan. A faulty relay could prevent the fan from turning on. Locate the fan relay, usually found in the fuse box or nearby, and consider replacing it if necessary.
Temperature Sensor: The temperature sensor monitors the engine's temperature and sends a signal to the fan relay to activate the fan when needed. A malfunctioning temperature sensor may not be accurately detecting the engine temperature, causing the fan not to turn on. You may need to replace the temperature sensor.
Wiring and Connections: Inspect the wiring and connections related to the radiator fan. Look for any loose, damaged, or disconnected wires or connectors. Ensure that the wires are properly connected and in good condition.
Fan Motor: If all the above components are functioning correctly, the issue may lie with the fan motor itself. Even though you have tested the fan and it works when connected directly, there could be an issue with the fan motor circuitry or the fan motor itself. In such cases, it may be necessary to have the fan motor inspected or replaced by a qualified mechanic.
If you're unsure about any of these steps or unable to resolve the issue yourself, it's recommended to consult a professional mechanic or bring your bike to a service center for a thorough diagnosis and repair.