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TROUBLESHOOTING
Table 4 — Thermostat 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.
‘‘Service Filter’’ is displayed on thermostat. After the configured number of blower operating hours, the Service
Filter message will be displayed. This reminds the owner to re-
place the filter. Reset the Service Filter feature to reset the blower
operation timer to 0 hours.
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 correctly and problem is with wiring or equip-
ment. If 24 vac is not present, replace the thermostat. Check for
Compressor Cycle per Hour Limit. Cooling may be locked out.
Heating will not energize. Select HEAT mode. Increase heating set point to 10 degrees above
room temperature. Check for 24 vac at W1/O/B terminal. If present,
thermostat is operating correctly and problem is with wiring or equip-
ment. If 24 vac is not present, replace the thermostat.
When using 4 wires (R,G,W,Y), the cooling equip-
ment tries repeatedly to turn on, but cannot. 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 equip-
ment tries repeatedly to turn on, but cannot. 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 3).
When calling for cooling, both heating and cool-
ing are energized.
The thermostat is configured for a heat pump. Configure the
thermostat for non-heat pump operation (Table 2, Step 3).
When controlling a commercial heat pump unit,
unit runs in reverse or heating is always on.
Commercial heat pumps require that Heat Pump Option on
thermostat is turned OFF.
Copyright 1998 Bryant Heating & Cooling Systems CATALOG NO. 809-683