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TROUBLESHOOTING
Symptom
No Heat/No Cool/No Fan
(common problems)
No Heat
No Cool
Heat, Cool or Fan Runs Constantly.
Furnace Cycles Too Fast or Too Slow
(narrow or wide temperature swing)
Cooling Cycles Too Fast or Too Slow
(narrow or wide temperature swing)
Thermostat Setting and Thermometer
Disagree
Clock Loses or Gains Time
Heat or Cool Starts Early
Thermostat Does Not Follow Program
Blank Display and/or Keypad Not
Responding
Possible Cause
1. Blown fuse or tripped circuit breaker.
2. Furnace power switch to OFF.
3. Furnace blower compartment door or
panel loose or not properly installed.
1. Pilot light not lit.
2. System Switch not set to Heat.
3. Loose connection to thermostat or system.
4. Furnace Lock-Out Condition. Heat may also
be intermittent.
5. Heating System requires service or
thermostat requires replacement.
1. System Switch not set to Cool.
2. Loose connection to thermostat or system.
3. Cooling System requires service or thermostat
requires replacement.
1. Fan Switch set to Fan On.
2. Possible short in wiring.
3. Possible short in thermostat.
4. Possible short in Heat/Cool/Fan system.
1. The location of the thermostat and/or the size
of the Heating System may be influencing the
cycle rate.
1. The location of the thermostat and/or the size
of the Cooling System may be influencing the
cycle rate.
1. Thermostat thermometer setting requires
adjustment.
1. Loss of power to thermostat and low batteries.
1. EMR activated
1. AM or PM set incorrectly in program.
2. AM or PM set incorrectly on the clock.
3. Voltage spike or static discharge.
1. Loss of power and dead batteries.
2. Voltage Spike or Static Discharge.
Corrective Action
Replace fuse or reset breaker.
Turn switch to ON.
Replace door panel in proper position to engage
safety interlock or door switch.
Re-light pilot.
Set System Switch to Heat and raise setpoint
above room temperature.
Verify thermostat and system wires are securely
attached.
Many furnaces have safety devices that shut the
system down when a lock-out condition occurs.
If the heat works intermittently contact the furnace
manufacturer or local service person for assistance.
Diagonistic: 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 contact
your heating and cooling service person or place
of purchase for a replacement. If the thermostat
clicks, contact the furnace manufacturer or a
service person to verify the heating system is
operating correctly.
Set System Switch to Cool and lower setpoint
below room temperature.
Verify thermostat and system wires are securely
attached.
Same procedure 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 if the compressor
lock-out option is selected in the configuration
menu (Item 6).
Check each wire connection to verify they are
not shorted or touching together. No bare wire
should stick out from under terminal screws. Try
resetting the thermostat as described below.
If the condition persists the manufacturer of
your system or service person can instruct you
on how to test the Heat/Cool system for correct
operation. If the system operates correctly,
replace the thermostat.
Item 2 in the Configuration Menu is the adjustment
that controls the cycle rate. If an acceptable cycle
rate is not achieved using the FA (Fast) or SL
(Slow) adjustment contact a local service person for
additional suggestions.
The cycle rate for cooling is fixed and can not be
adjusted. Contact a local service person for
suggestions.
The thermometer can be adjusted +/- 4 degrees as
listed in item 7 of the Configuration Menu. No other
adjustment is possible.
The thermostat will maintain its program in memory
even with no power/no batteries but the clock time
will be incorrect when power is restored. See No
Heat/No Cool/No Fan (common problems) above
for items to check in the system.
See Configuration Menu (Item 4).
Check current clock and program settings including
the AM or PM designations for each time period.
If a voltage spike or static discharge occurs use the
Reset Operation listed above.
Replace batteries and check heat/cool system for
proper operation. If a voltage spike or static discharge
occurs use the Reset Operation listed above.
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