Model	P21-050	P22-050	P32-050	P52-050	P72-050
Serial Number	V2200 thru V2947503	V2200 thru V2947503	V2200 thru V2947503	V2200 thru V2947503	V2200 thru V2947503

1.Remove electrical box cover. Check for broken or loose wiring. Refer to: Electrical Box Cover

2.Check high voltage on J12. Set meter to V. Place meter probes on black and white wires. Verify reading is 230V (115V for P21 models).

3.Check Low Voltage from transformer to low voltage wires on J1. Place meter probes on Yellow and Red wires. Verify reading is 24 volts.

4.Check high voltage incoming to box at J13.

5.Check Fuse F1 on board and in-line transformer fuse. Replace if needed & see if system starts. Refer to: Fuse

6.Bypass the remote switch to verify it is not defective. Disconnect the Red, White, and Blue wires from the remote switch. Connect the Blue and Red wires together. If the compressor runs (18 second delay), then replace remote wall switch or wiring.

Meter Required	Status	Required Action
High Voltage ≤ Line Voltage		Check incoming power
Low Voltage ≤ 24 Volts		Replace Transformer
High Voltage = Line Voltage		Check Fuse F1
Low Voltage = 24 Volts		Transformer OK

Model	P21-050	P22-050	P32-050	P52-050	P72-050
Serial Number	V2947504 thru Present	V2947504 thru Present	V2947504 thru Present	V2947504 thru Present	V2947504 thru Present

1.Remove electrical box cover. Inspect for loose, broken, or disconnected wiring. Refer to: Electrical Box Cover

2.Check mains voltage at J13 (power into PCB). Set meter to AC volts. Place probes on black and white wires at J13. Verify proper input voltage: 230V (P22-050, P32-050, P52-050, P72-050) or 115 VAC (P21-050). If incorrect, stop troubleshooting.

3.Check transformer primary voltage at J12. J12 should output the same mains voltage found at J13. Confirms the transformer is being powered. If no power, check fuse F1.

4.Check transformer secondary voltage at J1. Place meter probes on yellow and red wires at J1. Verify 24 Volts. If missing, transformer or wiring is faulty.

5.Check PCB DC power LEDs.
Verify internal supply LEDs are solid green:
- DS950 = 24 VDC
- DS450 = 15 VDC
- DS470 = 3.3 VDC
If any LED is off, the PCB cannot operate correctly. Replace PCB.

6.Verify controller status LEDs.
- DS20 OK LED should be blinking green (microcontroller running).
- DS21 Error LED should NOT be blinking red (no error condition).
If DS20 is not blinking or DS21 is flashing red, resolve before continuing.

7.Verify safety inputs (remote and thermal). DS720 REMOTE/THERMAL LED should be off. Solid red indicates the remote switch is OFF or the thermal switch is open. If DS720 is red, the compressor will not run. Bypass remote switch if needed.

8.Check pressure logic. If system pressure is below 80 PSI, DS200 PS_SW_EN STATUS LED should be solid green. This indicates the board is issuing the RUN command. If pressure is low but DS200 is not green, check pressure switch or logic input.

9.Verify motor enable output. If all conditions above are satisfied and the motor should be turning on, DS400 MOTOR_STATUS ENABLE LED should be solid green. This indicates output triacs/drivers are energized. If DS200 is green but DS400 is not, there is an output stage or motor safety issue. After a delay of 18 seconds from power up, DS200 should turn green. If DS200 does not turn green, replace PCB.

10.Check motor fuses.

LED Light	Label	Indicates
DS20	OK	Blinking green when operating normally.
DS21	ERROR	Continuous red flashing when there is an error in the system.
DS720	REMOTE/THERMAL ERROR	Solid RED when remote switch open or thermal switch closed.
DS200	PS_SW_EN STATUS	LED turns solid green when sending run command to motor.
DS400	MOTOR_STATUS ENABLE	Triacs are Enabled (Motors should be running).
DS450	15 VDC	Solid green when 15VDC circuit is functional.
DS470	3.3 VDC	Solid green when 3.3VDC circuit is functional.
DS950	24 VDC	Solid green when 24VDC circuit is functional.

Meter Required	Status	Required Action
High Voltage ≤ Line Voltage		Check incoming power
Low Voltage ≤ 24 Volts		Replace Transformer
High Voltage = Line Voltage		Check Fuse F1
Low Voltage = 24 Volts		Transformer OK