Analysis:
1. "220V Cooling Fan"Power barrier;
2. burn insurance;
3. "220V Cooling Fan"Temperature switch bad;
4. Transformer / HV Diode / time power dividers / magnetron loose wiring or destroyed;
5. "220V Cooling Fan"voltage drops below 187 volts, can not start. Solution: Check the power supply, fuse and all the main circuit components and wiring.