6
Pub. No. 18-HD29D2-4
Installer’s Guide
Table 4
Troubleshooting
Symptom
Possible Cause
Action
Display will not come on.
1. Blown fuse or tripped circuit breaker.
2. Furnace power switch OFF.
3. Furnace blower compartment door or panel
loose or not properly installed.
1. Replace fuse or reset breaker.
2. Turn switch to ON.
3. Replace door panel in proper position to engage safety interlock or
door switch.
Indoor temperature display is
incorrect.
Temperature display needs calibration.
Calibrate Sensor - User Setup Step 49.
Outdoor temperature display is
incorrect.
Temperature display needs calibration.
1. Calibrate Sensor - User Setup Step 50.
2. Disconnect outdoor sensor from controls terminal block and check the
sensor and field wiring reisitance value - Table 2.
Outdoor temperature display
shows "--" and Service indicator
on solid.
Outdoor temperature sensor open or shorted
Outdoor sensor field wiring open or shorted
1. Replace outdoor sensor.
2. Check / repair outdoor sensor field wiring.
Cannot set Heating setpoint
above 80 degrees
Deadband between Heating and Cooling set to high
Decrease Deadband setting - User Setup Step 42.
Service indicator Flashing on and
off.
Control EEPROM write error.
Press any key and Check / Re-enter Setup Choices.
Service indicator solid on and "--"
in temperature display.
Indoor temperature sensor open or shorted
Replace Control
Temperature setting will not
change. (Example: Cannot set
heating higher or cooling lower).
1. Upper and/or lower temperature limits were
reached.
2. "Keypad locked" is displayed on LCD.
1. Check the temperature setpoints:
Heating limits are 40 - 85F.
Cooling limits are 65 - 90F.
2. Unlock keypad - press Up+Down arrow together until icon disappears.
Room temperature overshoots
when Energy Savings Key ($) is
used or the Heat/Cool settings is
changed more than 2 degrees.
Oversized heating or cooling equipment. Control
can not respond fast enough to prevent
overshooting.
Set Control Response rate to "Fast" - Step 33.
Heating will not come on.
1. System Mode not set to Heat.
2. Minimum off time delay being enforced.
3. Loose connection to control or system.
4. Heating system requires service or
control requires replacement.
1. Set Mode to heat and raise the setpoint above room temperature.
2. If heating does not come on within 5 minutes, Check Heating.
3. Check - Repair connections.
4. Repair system / Replace control.
Cooling will not come on.
1. System Mode not set to Cool.
2. Minimum off time delay being enforced
3. Loose connection to control or system.
4. Cooling system requires service or
control requires replacement.
1. Set Mode to cool and lower the setpoint below room temperature.
2. If cooling does not come on within 15 minutes, contact servicer.
3. Repair connections.
4. Repair system / Replace control.
Cool ON or Heat ON is displayed,
but no warm or cool air is coming
from the registers.
1. The heating equipment turns on the
fan when the furnace has warmed up to a
setpoint.
2. Heating or cooling equipment is not
operating.
1. Wait one minute after Heat ON is displayed
and then check the registers.
2. Check Heating and Cooling system.
Control does not respond to
keypad presses.
1. "Keypad locked" is displayed on LCD.
2. Keypad failure.
1. Unlock keypad - press Up+Down arrow together until "Keypad locked"
appears.
2. Replace Control.
Fan does not operate properly in
heat or cool mode.
1. Incorrect wiring.
2. Heating or cooling equipment inoperative.
1. Correct wiring.
2. Repair system.
Fan runs all the time.
1. Fan mode set to ON.
2. Shorted control wiring.
1. Set fan mode to AUTO.
2. Check / Repair wiring.
Cooling cycle too fast or too slow.
(Narrow or wide temperature
swing).
The location of the control and/or the size of the
cooling system may be influencing the cycle rate.
Verify cycle rate adjustment Step 19.
Heating cycle too fast or too slow.
(Narrow or wide temperature
swing).
The location of the control and/or the size of the
heating system may be influencing the cycle rate.
Verify cycle rate adjustment Step 27.
Troubleshooting
