White Rodgers 750 User Manual

Symptom

Possible Cause

Corrective Action

No Heat (continued)

5. Heating system requires service or

Diagnostic: Set SYSTEM Switch to HEAT and

raise thermostat requires replacement.

the setpoint above room temperature. Within a few
seconds the thermostat should make a soft click
sound. This sound usually indicates the thermo-
stat 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 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
attached.

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.

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.

suggestions.

Thermostat Setting and Thermostat

1. Thermostat thermometer setting requires

The thermometer can be adjusted +/- 3 degrees.

Thermometer Disagree

adjustment.

See Temperature Display Adjustment in the

Operation section.

Thermostat Does Not Follow Program

1. AM or PM set incorrectly in program.

Check current clock and program settings

2. AM or PM set incorrectly on the clock.

including the AM or PM designations for each

3. Voltage spike or static discharge.

time period. If a voltage spike or a static discharge
occurs use the Reset Operation listed above.

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.

TROUBLESHOOTING