Troubleshooting - Carrier 53DFS250-HW Installation Manual

Troubleshooting

Symptom
Display does not come
on.
Temperature settings
do not change.
Heating or cooling
does not come on.
Heat does not turn on
(Heat On is solid in the
display).
Cooling does not turn
on (Cool On is solid in
the display).
Heat On is not in the
display.
Cool On is not in the
display.
Wait is in the display.
Possible Cause
Thermostat is not being
powered.
The upper or lower temperature
limits were reached.
The keypad is fully locked.
Thermostat minimum off-time is
activated.
System selection not set to Heat
or Cool.
System type Selection is
incorrect.
Heating equipment failure.
Loose or broken wire
connection between thermostat
and heating equipment.
Cooling equipment failure.
Loose or broken wire
connection between thermostat
and cooling equipment.
System setting is not set
to Heat and/or temperature
setting is not set above room
temperature.
System setting is not set to
Cool and/or the temperature
setting is not set below room
temperature.
Compressor minimum off timer
is active.
Action
Check for 24 Vac between C and R. Check that AA
batteries are installed correctly and are good.
Check temperature setpoints. Check Installer Setup
Numbers 0600 and 0610; modify as needed.
Check Installer Setup Number 0670 to change
keypad locked options.
Wait up to five minutes for the system to respond.
Set system Selection to correct position.
Check Installer Setup Number 0170 and make sure
correct System type is chosen.
Check for 24 Vac at the equipment on the secondary
side of the transformer between power and
common. If voltage is not present, check the heating
equipment to find the cause of the problem.
Check for 24 Vac between the heat terminal (Y and
H2) and transformer common. If 24 Vac is present,
the thermostat is functional. Check the heating
equipment to find the cause of the problem.
Check for 24 Vac between the heat terminal (Y
and H2) and transformer common. If voltage is not
present, check wire connection (loose or broken)
between the thermostat and the heating equipment.
Check for 24 Vac at the equipment on the secondary
side of the transformer between power and
common. If voltage is not present, check the cooling
equipment to find the cause of the problem.
Check for 24 Vac between the cool terminal (Y)
and transformer common. If 24 Vac is present,
the thermostat is functional. Check the cooling
equipment to find the cause of the problem.
Check for 24 Vac between the cool terminal (Y)
and transformer common. If voltage is not present,
check the wire connection (loose or broken)
between the thermostat and the cooling equipment.
Set the system setting to Heat and set the
temperature setting above the room temperature.
Set the system setting to Cool and set the
temperature setting below the room temperature.
Wait up to five minutes for the cooling or heating
(heat pump) equipment to turn on.
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53DFS250-HW
69-2565—05