Troubleshooting – White Rodgers Thermostat 1F78 User Manual

Page 6

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Possible Cause

Corrective Action

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.

stick out from under terminal screws. Try resetting

4. FAN Switch set to Fan ON.

the thermostat as described above 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

Digital thermostats normally provide precise

(narrow or wide temperature swing)

size of the Heating System 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 and 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, clip Jumper W-905 as
mentioned in the instructions for Hydronic Heating
Systems. It is not possible to shorten the cycle
time. If an acceptable cycle rate is not achieved as
received or by clipping W-905 contact a local
service person for additional suggestions.

Cooling Cycles Too Fast or Too Slow

1. The location of the thermostat and 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

cycle rate.


Thermostat Setting and Thermostat

1. Thermostat thermometer setting requires

The thermometer can be adjusted +/- 3 degrees.

Thermometer Disagree


See Temperature Display Adjustment in the

Operation section.

Blank Display and/or Keypad

1. Voltage spike or static discharge.

Replace batteries and check heat/cool system

Not Responding

2. Battery change required.

for proper operation. If a voltage spike occurs use
the Reset Operation listed above.




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