heat-timer EPU-D Installation And Operation Manual page 41

Symptom
No display or No power to the EPU‐D
distorted display. Control Module, incorrect
or defective wiring.
Display shows Sensor disconnected.
sensor "Open".
Defective sensor, wires, or
EPU‐D Control Module.
Display shows Defective sensor, wires, or
sensor "Short". EPU‐D Control Module.
Display shows an Defective EPU‐D Control
incorrect Module, sensor, or wiring.
temperature.
Heat‐Timer Corp.
Troubleshooting
Possible Cause Recommended Action(s)
Verify the EPU‐D Control Module is receiving power, all power
wiring is in good condition and connected.
The EPU‐D Control Module requires 120Vac power to terminal
1 and 2, and earth ground wiring to terminal 3.
Turn power to the EPU‐D Control Module off then back on.
See "Power Input Wiring" on page 16.
Verify the sensor is properly connected to the EPU‐D Control
Module.
Disconnect the sensor input wires from the control and use an
Ohm meter to measure the resistance between the sensor
wires. Refer to Table 2 on page 43.
• If the readings are out of range, the sensor or the wiring
may be defective. Replace the sensor/wiring.
Connect the sensor wires to the control and disconnect the
wires from the sensor terminals. Short the wires together.
• If the display still reads "Open", the control is defective.
Replace the EPU‐D Control Module.
Remove the wires from the sensor terminals. The display
should read "Open".
• If the display still reads "Short", the control is defective.
Replace the EPU‐D Control Module.
• If the display reads "Open", the sensor may be defective.
Replace the sensor/wiring.
Remove the wires from the sensor terminals. The display
should read "Open".
• If the display does not read "Open", the control is
defective. Replace the EPU‐D Control Module.
Use an Ohm meter to measure the resistance between the
sensor wires. Refer to Table 2 on page 43.
• If the readings are out of range, the sensor or the wiring
may be defective. Replace the sensor/wiring.
Troubleshooting 41
059840‐00 Rev. A