Usually I just use these methods to check the fan.
- Try using 3-Pin to Molex converter and see if the fan spin.
- Also make sure that fan is loose or can spin properly. Try spinning it with your finger.
- Some PC case have a thin layer sponge as a dust filter and usually it's for the front fan. The sponge can touch the fan and making it not able to spin.
- Try other fan socket on the motherboard. You can use the 4-pins socket on the motherboard with 3-pins connector.