As an HVAC technician, understanding how to find common, start, and run on a PSC (Permanent Split Capacitor) compressor motor is crucial for troubleshooting and maintenance. Here’s a step-by-step guide to help you identify these terminals:
Step 1: Safety Precautions
Before starting, ensure that the power to the compressor is turned off to prevent any electrical hazards.
Step 2: Set Multimeter
Set your multimeter to the ohms setting. Ensure that the probes are not touching, so the multimeter reads “OL” (open loop).
Step 3: Testing Resistance
- Test each terminal of the compressor motor by placing the multimeter probes on the terminals.
- Record the resistance values for each pair of terminals.
Step 4: Identifying Terminals
- The terminal with the highest resistance reading is the common terminal.
- The terminal with the second-highest resistance reading is the start terminal.
- The terminal with the lowest resistance reading is the run terminal.
Step 5: Understanding the Readings
- The common terminal is where both windings connect, resulting in the highest resistance.
- The start terminal has the second-highest resistance and is connected to the start winding.
- The run terminal has the lowest resistance and is connected to the run winding.
Step 6: Verification
To verify your findings, cross-reference the identified terminals with the compressor motor’s wiring diagram.
By following these steps, you can accurately identify the common, start, and run terminals on a PSC compressor motor, enabling you to perform effective troubleshooting and maintenance.
Remember, safety should always be a priority when working with electrical components. If you are unsure or uncomfortable with these procedures, it’s best to consult a qualified HVAC professional.
