TROUBLESHOOTING
Table4—Troubleshooting
PROBLEM SOLUTION
Display on thermostat not illuminated. Check for 24 vac at the R terminal connection. Terminal
R must be connected for proper thermostat operation.
Cooling will not energize. Select COOL mode. Decrease cooling set point to
10 degrees below room temperature. Check for 24 vac
at Y1 terminal. If present, thermostat is operating cor-
rectly and problem is with wiring or equipment. If 24 vac
is not present, replace the thermostat. Check for Com-
pressor Cycle per Hour Limit. Cooling may be locked
out.
Heating will not energize. Select HEAT mode. Increase heating set point to 10 de-
grees above room temperature. Check for 24 vac at W1/
O/B terminal. If present, thermostat is operating correctly
and problem is with wiring or equipment. If 24 vac is not
present, replace the thermostat.
When using 4 wires (R,G,W,Y), the cooling
equipment tries repeatedly to turn on, but can-
not. At times the display dims or disappears.
There is not enough power available. Connect a
270 ohm, 10 watt power resistor at the air conditioning
equipment between terminals W and C (non-heat pump
applications only).
When using 4 wires (R,G,W,Y), the heating
equipment tries repeatedly to turn on, but can-
not. At times the display dims or disappears.
There is not enough power available. Connect a
270 ohm, 10 watt power resistor at the air-conditioning
equipment between terminals Y and C (non-heat pump
applications only).
When controlling a heat pump, heat comes on
during cooling cycle.
Configure thermostat for heat pump operation (Table 2,
Step 5).
When calling for cooling, both heating and
cooling are energized.
The thermostat is configured for a heat pump. Configure
the thermostat for non-heat pump operation (Table 2,
Step 5).
When controlling a commercial heat pump
unit, unit runs in reverse or heating is always
on.
Some commercial heat pumps require that Heat Pump
Option on thermostat is turned OFF. Refer to unit instal-
lation instructions for more information.
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