Symptom
Possible Cause
Corrective Action
No Heat/No Cool/No Fan
1. Blown fuse or tripped circuit breaker.
Replace fuse or reset breaker.
(Common Problems)
2. Furnace power switch to OFF.
Turn switch to ON.
3. Furnace blower compartment door or
Replace door panel in proper position to engage
panel loose or not properly installed.
safety interlock or door switch.
No Heat
1. Pilot light not lit.
Re-light pilot.
2. System button not pressed to display Heat.
Set SYSTEM button until HEAT is displayed and
raise temperature above room temperature.
3. Loose connection to thermostat or system.
Verify thermostat and system wires are securely
attached.
4. Furnace Lock-Out Condition. Heat may also
Many furnaces have safety devices that shut
be intermittent.
down when a lock-out condition occurs. If the
heat works intermittently contact the furnace
manufacturer or local service person for
assistance.
5. Heating system requires service or
Diagonistic: Set SYSTEM button until HEAT is
displayed and raise 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 on the previous page. If the
thermostat does not click after being reset contact
your heating and cooling service person or place
of purchase for replacement. If the thermostat
clicks, contact the furnace manufacturer or a service
person to verify the heating is operation correctly.
No Cool
1. System button not pressed to display Cool.
Set SYSTEM button until COOL is displayed and
lower temperature below room temperature.
2. Loose connection to thermostat or system.
Verify thermostat and system wires are securely
attached.
3. Cooling system requires service or
Same procedure as diagnostic for No Heat
thermostat requires replacement.
condition except press the SYSTEM button until
COOL is displayed and lower the setpoint below
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.
Check each wire connection to verify they are not
2. Possible short in thermostat.
shorted or touching together. No bare wire should
3. Possible short in Heat/Cool/Fan system.
out from under terminal screws. Try resetting the
4. Fan button pressed to display FAN ON.
thermostat as described on the previous page. 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.
Furnace Cycles Too Fast or Too Slow
1. The location of the thermostat and/or the size
Digital thermostats normally provide precise
(narrow or wide temperature swing)
of the Heating System equipment may be
temperature control and may cycle faster than
influencing the cycle rate.
some older mechanical models. A faster cycle
rate means the unit turns on on off more frequently
but runs for a shorter time so there is no increase
in energy use. If you would like to increase the
cycle time, refer to page 6 under Installer Table for
settings. If an acceptable cycle rate is not acheived
by the adjustment in the Installer Table then you
may want to contact a local heating and air
conditioning service person for further suggestions.
Cooling Cycles Too Fast or Too Slow
1. The location of the thermostat and/or the size
The cycle rate for cooling is fixed and can not be
(narrow or wide temperature swing)
of the Cooling System can influence the
adjusted. Contact a local service person for
rate.
suggestions.
TROUBLESHOOTING
10
