Compressor doesn't start?

On the diagram this

would be a pressure switch. That would be the second thing to check after the on/off switch. You should be able to see resistance on the 2 terminals of the power plug with the on/off switch on. If not, short out the pressure switch and see if resistance shows - it should be relatively low, 1-5Ω.

If there is no reading then you might have a bad motor. Try reading directly on the motor leads.

BAsically.

Troubleshooting the Motor:
If the motor doesn't start, common checks include:

• Confirming proper power supply (breaker/fuse).
• Checking for proper extension cord use (avoiding overly long or thin cords).
• Letting the motor cool down if the thermal overload has tripped.
• Issues with the pressure switch or internal components like reed valves or brushes if it runs but doesn't build pressure.