Troubleshooting - Carrier 33CS Installation, Start-Up, And Operating Instructions Manual

PROBLEM
Display on thermostat not illuminated.
''Service Filter'' is displayed on thermostat.
Cooling will not energize.
Heating will not energize.
When using 4 wires (R,G,W,Y), the cooling equipment
tries repeatedly to turn on, but cannot. At times the
display dims or disappears.
When using 4 wires (R,G,W,Y), the heating equipment
tries repeatedly to turn on, but cannot. At times the
display dims or disappears.
When controlling a heat pump, heat comes on during
cooling cycle.
When calling for cooling, both heating and cooling are
energized.
When controlling a commercial heat pump unit, unit
runs in reverse or heating is always on.
The thermostat temperature display rises to 99 F.
The resistor labeled "L3" on the thermostat is burned
out and brown. Thermostat will not work.

TROUBLESHOOTING

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Table 4 — Thermostat Troubleshooting
Check for 24 vac at the R terminal connection. Terminal R must be
connected for proper thermostat operation.
After the configured number of blower operating hours, the Service Filter
message will be displayed. This reminds the owner to replace the filter.
Reset the Service Filter feature to reset the blower operation timer to 0
hours.
Select COOL mode. Decrease cooling set point to 10 degrees below room
temperature. Check for 24 vac at Y1 terminal with a load connected. If
present, thermostat is operating correctly 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.
Select HEAT mode. Increase heating set point to 10 degrees above room
temperature. Check for 24 vac at W1/O/B terminal with a load connected. If
present, thermostat is operating correctly and problem is with wiring or
equipment. If 24 vac is not present, replace the thermostat.
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).
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).
Configure thermostat for heat pump operation (Table 2, Step 3).
The thermostat is configured for a heat pump. Configure the thermostat for
non-heat pump operation (Table 2, Step 3).
Commercial heat pumps require that Heat Pump Option on thermostat is
turned OFF.
There is not enough voltage to the thermostat. Check wiring and power
supply.
The thermostat has been wired incorrectly and the circuit board is burned
out. Thermostat must be replaced.
9
SOLUTION
1204