Specifications, Troubleshooting – White Rodgers Thermostat 1F78 User Manual

Page 5

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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 Switch not set to HEAT.

Set SYSTEM Switch to HEAT and raise setpoint
temperature above room temperature.

3. Loose connection to thermostat or system.

Verify thermostat and system wires are securely

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

5. Heating system requires service or

Diagnostic: Set SYSTEM Switch to HEAT and

thermostat requires replacement.

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 below.
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 manufac
turer or a service person to verify the heating is
operating correctly.

No Cool

1. SYSTEM Switch not set to Cool.

Set SYSTEM Switch to COOL and lower setpoint
temperature below room temperature.

2. Loose connection to thermostat or system.

Verify thermostat and system wires are securely

3. Cooling system requires service or

Same procedure as diagnostic for No Heat

thermostat requires replacement.

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.



Electrical Rating:

0 to 30 VAC 50/60 Hz. or D.C.
0.05 to 1.0 Amps (Load per terminal)
1.5 Amps Maximum Total Load (All terminals combined)



Setpoint Temperature Range:



F to 90


F (7


C to 32



Operating Ambient Temperature Range:



F to 105



Operating Humidity Range:

0 to 90% RH (non-condensing)

Shipping Temperature Range:



F to 150




Reset Operation
If a voltage spike or static discharge blanks out the display or
causes erratic thermostat operation you can reset the thermo-
stat by pressing


at the same time while moving

the SYSTEM switch from OFF to HEAT. This also resets the
factory defaults. If the thermostat has power, has been reset

and still does not function correctly contact your heating/cooling
service person or place of purchase.

For optimum performance, we recommend replacing batteries
once a year with fresh “AAA” Energizer


alkaline batteries.