Troubleshooting
Reset Operation
Note:
1. When thermostat is reset, installer configuration menu settings and programming will reset to factory settings.
If a voltage spike or static discharge blanks out the display or causes erratic thermostat operation, you can reset the
thermostat by removing the wires from terminals R and C (do not short them together) and removing batteries for 2
minutes. After resetting the thermostat, replace the wires and batteries. If the thermostat has been reset and still does not
function correctly contact your heating/cooling service person or place of purchase.
2.Be sure to review the installer configuration menu settings.
To reset the programming, clock and configuration settings, press the
and
and SYSTEM keys simultaneously. The
thermostat should go blank and then all segments will be displayed momentarily.
Symptom
Possible Cause
Corrective Action
No Heat/No Cool/No Fan
(common problems).
1. Blown fuse or tripped circuit breaker.
2. Power switch to OFF.
3. Fan compartment door or panel loose or not properly
installed.
4. Loose connection to thermostat or system.
1. Replace fuse or reset breaker.
2. Turn switch to ON.
3. Replace door panel in proper position to engage safety inter-
lock or door switch.
4. Tighten connections
No Heat
1. Lock-Out Condition. Heat may also be intermittent.
2. Heating system requires service or thermostat requires
replacement.
If the heat works intermittently, contact a local HVAC service
person for assistance.
Diagnostic:
Set SYSTEM Switch to
HEAT
and raise the
setpoint above room temperature. Within a few seconds
the thermostat should make a soft click sound. This sound
usually indicates the thermostat is operating properly. If
the thermostat does not click, try the reset operation listed
above. If the thermostat does not click after being reset, replace
the thermostat and contact an HVAC service person to verify the
heating is operating correctly.
No Cool
1. Cooling system requires service or thermostat requires
replacement.
Same as diagnostic for No Heat condition except set the
thermostat to
COOL
and lower the setpoint below the
room temperature. There may be up to a five minute delay
before the thermostat clicks in Cooling.
Heat, Cool or Fan
Runs Constantly
1. Possible short in wiring.
2. Possible short in thermostat.
3. Possible short in heat/cool/fan system.
4. FAN switch set to Fan ON.
Check each wire connection to verify they are not shorted
or touching together. No bare wire should stick out from
under terminal block. Try resetting the thermostat as described
above. If the condition persists, test the Heat/Cool system for
correct operation. If the system operates correctly, replace the
thermostat.
Thermostat Setting &
Thermostat Thermometer
Disagree
1. Thermostat thermometer setting requires adjustment.
The thermometer can be ad/- 5 degrees. See "11. Select
Temperature Display Adjustment" on
page 8
.
Water Source Heat Pump Cycles
Too Fast or Too Slow
(narrow or wide
temperature swing)
1. The location of the thermostat and/or the size of the
Heating System may be influencing the cycle rate.
Digital thermostats provide precise control and cycle
faster than older mechanical models. The system turns
on and off more frequently but runs for a shorter time
so there is no increase in energy use. If you would like
an increased cycle time, choose SL for slow cycle in the
"Installer/Configuration Menu" on page 7
, step 6 (heat) or 7
(cool). If an acceptable cycle rate is not achieved, contact a local
HVAC service person for additional suggestions.
Forgot Keypad
Lockout Code
Press the menu key (key will disappear) and hold in for
20 seconds. This unlocks the thermostat.
Blank display any or keypad
not responding
1. Voltage Spike or static discharge
Use the Reset Operation shown above.
Thermostat does not have
Menu Screen Numbers
1. Earlier version of thermostat
Contact your local Daikin factory representative.
©2013 Daikin Applied •
www.DaikinApplied.com
• 800.432.1342
IOM 1178-1 / Page 16 of 16
