Troubleshooting Guide
IF...
Display will not come on.
Temperature display will not go lower
than 45° F
r“
C] or higher than 88° F
[31
0
C]
during programming.
Temperature change occurs at the
wrong times.
Heating will not come on.
THEN...
Set the system switch to
OFF. Remove batteries.
Insert batteries backward for
at least five seconds to
reset thermostat. Replace batteries correctly. Display
should come on.
Make sure batteries are fresh and installed correctly.
Gently clean battery contacts using a soft pencil
eraser. Do not use anything abrasive on clips.
You have reached the temperature setting limit.
The setting range is 45° F to 88°F [7°Cto310 C].
Check the program times for the period in
question. Be sure that AM and PM indications
are correct. Make sure the current day and time are
correct. Reprogram if necessary.
Check that switch on thermostat is set to HEAT.
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Heating will not come on (continued).
9
Cooling will not come on.
The house is too warm or too cool.
SYSTEM ON indicator is lit, but no
heat is coming from the registers.

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Check the system fuse or circuit breaker and replace
or reset if necessary.
Check for correct wiring and good connections.
Jumper wires R and W. If heat does not come on,
contact your heating dealer.
If display is blank or says “bAt Lo,” install fresh
batteries.
If temperature setting is higher than current tempera-
ture, and SYSTEM ON indicator is lit, contact
Honeywell Customer Assistance at 1-800-468-1502.
Check that switch on thermostat is set to COOL.
Check the system fuse or circuit breaker and replace
or reset if necessary.
Check for correct wiring and good connections.
Jumper wires
Rc
and Y. If cooling does not come on,
contact your cooling dealer.
If display is blank or says “bAt Lo,” install fresh
batteries.
The thermostat has a built-in time delay on cooling.
Allow five to ten minutes after changing the setting
before the air conditioner starts.
30
Make sure outdoor disconnect is engaged (on).
If temperature setting is lower than current tempera-
ture, and SYSTEM ON indicator is lit, move system
switch from COOL to OFF for ten minutes. After ten
minutes, return switch to COOL position. If air
conditioner comes on, compressor may have reached
its high limit temperature protection and shut down. If
air conditioner does not come on after the ten minutes
and the SYSTEM ON indicator is lit, contact Honey-
well Consumer Assistance at 1-800-468-1502.
If 2- or 4-wire installation,
verify that R-Rc jumper is
installed.
Press RUN PROGRAM key to check the current
temperature setting.
f desired, change the temperature setting. See
)age
14.
Wow
time for the furnace to heat up and the fan to
:ome
on before checking for heat at the register.
Check
to make sure system on-time is set
:orrectly
according to pages 16 and 17.)
31