QD Boxes are designed for use with 3-wire, single phase submersible motors from ? to 1 hp. Troubleshooting inside the box is made simple by the control components automatically disconnecting from the system when the lid is removed.

I have outlined some troubleshooting steps below to help investigate problems with your QD Control Box.

Caution! Electricity can be very dangerous, especially if you are inexperienced. Always use caution working with electricity and turn off power supply breakers when testing components within the electrical system. If you are not 100% confident you can perform any of these tests safely, call a professional.

Standard QD’s contain just a start capacitor and QD relay. The old QD CRC boxes (Capacitor Run Capacitor Start) also contain a run capacitor. The incoming power is attached at L1 and L2. The pump wires connect to R, Y, and B. R (red) is the start winding, Y (yellow) is the common, and B (black) is the run winding. When the motor is started, both the start and main windings are energized. As the motor approaches running speed, the start capacitor and the start winding must be disconnected, and the motor operates on the run winding alone. The job of the QD relay is to remove, or disconnect, the start capacitor and start winding as the motor reaches running speed. In the QD CRC Box the start capacitor and start winding are disconnected just like above, however, the start winding and the run capacitor(s) stay connected and working, even when the motor is at running speed.

1. Check the capacitor(s). Using an ohmmeter set to R X 1,000, place your leads on either of the contactor terminals. The meter should swing toward zero, then back to infinity. One unfortunate and important note for this test is that a capacitor that has lost some capacitance may test okay, however, it may no longer function properly.
2. Check the QD relay. Using an ohmmeter set to R X 1,000 you will perform what is know as the triac test. Connect meter leads to the capacitor and B terminals and you should get an infinity reading.
3. Coil test. Using an ohmmeter, set your meter to R x 1. Connect meter leads to L1 and B and the correct reading is Zero ohms for all models.

Now that all components have been tested and assuming the problem persists we will begin performing the voltage and amperage tests.

Warning: The power must be on for these tests. Do not touch any live parts. If you are not comfortable or are inexperienced working with hot wires contact a professional.

1. Measure Voltage. Ensure that the motor is off and measure voltage at L1 and L2 of pressure switch or line contactor. The reading should be +/- 10% of motor rating. With the motor running, measure voltage at the load side of pressure switch or line contactor. The voltage reading should remain the same except for a slight dip on starting. Excessive voltage drop can be caused by loose connections, bad contacts, ground faults, or inadequate power supply. Relay chatter is caused by low voltage or ground faults.

Hopefully this blog has given you some insight or a solution to your problem. You can also check out our video titled “How to Troubleshoot a QD Control Box” on the RC Worst YouTube Channel or give our experts a call at 855.329.4519.