TROUBLESHOOTING GUIDE
IF... THEN...
Thermostat loses program.
❑
Check for loose battery.
❑ Check that power switch is ON.
Thermostat shows no display,
❑ Check that power switch is ON.
unless HEAT or COOL key is held.
•l Check main switches, fuse and circuit breakers
on heating equipment to make sure the thermostat
has power. The heating control circuit powers the
thermostat even when it is controlling air condition-
ing equipment.
❑ Check the wiring connections to the thermostat.
❑ Make sure your system uses 24 Vat. The
thermostat will not operate on a millivolt system.
❑ Jumper
RC
& Y or RH & W. If system comes on,
thermostat needs replacement. If system does not
come on, a problem exists in the system (such as
transformer, relay or valve).
32
Troubleshooting Guide continued
IF...
Display goes blank less than 30
seconds before or after a furnace
burn cycle.
Display goes blank for several
minutes during a long furnace burn
cycle.
Temperature display is incorrect.
THEN...
❑ Your furnace is interrupting power to the
thermostat. This is not a problem, as the 9 V
alkaline battery will be adequate to carry the
program for the entire heating season. Do NOT
use a rechargeable battery.
❑ Check for dirty air filters or blocked registers. If
registers are not blocked and the air filter is clean,
an isolating relay probably needs to be installed on
your heating system. See Table 1 in the installation
manual, form number 69-8025.
•l See “Recalibrating the Thermostat,” page 29.
33 69-8026—2
Troubleshooting Guide continued
IF... THEN...
Furnace or air conditioner ❑ Check the thermostat to see if it is wired properly.
operates continuously.
❑ Check the furnace and air conditioning systems to
make sure they are operating correctly.
Thermostat will not turn heat or •l Check
circuk
breaker on heater or air conditioner
air conditioner on. to make sure it has power.
❑ Check that pilot light/power is on; this thermostat
“steals” power from the heating circuit.
❑ Verify wiring.
Thermostat will not let you make ❑ Check if you have already made 6 settings. A
a temperature setting. maximum of 6 settings per day are available. The
thermostat will not accept a seventh setting.
❑ Check if you have used all 8 available temperature
combinations. A maximum of 8 heating and cooling
combinations are allowed in total in your weekly
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