Troubleshooting (Table 11) - Honeywell VisionPRO TB8220 User Manual

TROUBLESHOOTING (TABLE 11)

Symptom
Display does not come on.
Temperature settings do not
change.
Heating or cooling does not come
on.
Thermostat is calling for Heat
(Heat on) or Cool (Cool on) but
no heating or cooling is running.
Heat does not turn on (Heat On is
solid in the display).
Cooling does not turn on (Cool
On is solid in the display).
Fan does not turn on in a call for
heat (electric furnace).
Heat pump puts out cool air in the
heat mode and warm air in the
cool mode.
Both the heating and cooling
equipment are running at the
same time.
TB8220 COMMERCIAL VISIONPRO™ PROGRAMMABLE THERMOSTAT
Table 11. Troubleshooting.
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. Wait up to five minutes for the system to respond.
System selection is not set to Heat or Cool. Set system Selection to correct position.
System type Selection is incorrect.
Heating or cooling equipment is not
operating.
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.
Fan Control in Heating is set to Gas or Oil
Furnace (Setting 0180).
Changeover Valve (ISU 0190) is not
configured to match the changeover
required by the installed heat pump.
The heating equipment is not a heat pump
but the System Type (ISU 0170) is set to
Heat Pump.
Heating and cooling wires are shorted
together.
23
Action
Check for 24 Vac between C and Rc.
Check that AAA batteries are installed correctly
and are good.
Check temperature setpoints.
Check ISU 0600 and 0610; modify as needed.
Check ISU 0670 to change keypad locked
options.
Check ISU 0170 and make sure correct System
type is chosen.
Check wiring.
Check ISU 0170 and make sure correct system
type is chosen.
Verify operation of equipment in System Test
mode.
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 (W)
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 (W)
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 Fan Control in Heating to Electric Furnace
(Setting 0180).
Set Changeover Valve (ISU 0190) to match the
changeover required by the installed heat pump.
Set System Type (ISU 0170) to match the
installed heating and/or cooling equipment.
Separate the shorted heating and cooling wires.
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