Troubleshooting; Fan Control - Honeywell TB6575 SuitePRO Installation Instructions Manual

TB6575/TB8575 SUITEPRO™ DIGITAL FAN COIL THERMOSTATS
When the pipe sensor senses that the pipe temperature is out of
limitation and needs to change over, the purging function will turn
on for 5 minutes.
If the fan speed is set to Auto and purging is on, the fan turns on
only when there is a call for Heat or Cool. If there is no call for
Heat or Cool, the fan does not turn on. In summary, fan control is
never called by the purging function; it turns on if there is a call
for Heat or Cool.

Fan Control

All models support Constant and Cycle fan modes depending on
configuration.
When the fan status is in the low, medium, or high speed, "Low"
"Med", or "Hi" respectively displays on the LCD. When the fan
status is in auto, "Auto" displays on the LCD.
NOTE: "Auto" displays on the LCD when Cycle fan mode is
active.
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).
Both the heating and
cooling equipment are
running at the same
time.
62-0278—01
Possible Cause
Thermostat is not being
powered.
The upper or lower
temperature limits were
reached.
The keypad is fully locked.
System Type selection not
set to Heat or Cool or the
selection is incorrect.
Heating or cooling equipment
is not operating.
Heating equipment failure.
Loose connection or broken
wire between thermostat and
heating equipment.
Incorrect System Type
selected.
Heating and cooling wires are
shorted together.
NOTE: See "Auto Fan Reset" on page 13.

TROUBLESHOOTING

Table 6 provides troubleshooting information.
Table 6. Troubleshooting.
For TB6575A/B, check for 120/240 Vac between L and N.
For TB8575A, check for 24 Vac between R and C.
Check the temperature setpoints for heating and cooling (Installer Setup
codes 16 and 17 respectively). Modify as needed.
Change keypad locked options (Installer Setup code #18).
Set the Installer Setup code #2 (System Type) to the correct value to match
the installed heating and/or cooling equipment. Verify operation of wiring
and equipment in Installer Test mode.
Check wiring. Check that the Installer Setup code #2 (System Type) value
matches the installed heating and/or cooling equipment. Verify operation of
equipment in Installer Test mode.
For TB6575A/B:
1. Check for 120/240 Vac at the equipment between power and
common, (terminals L and N).
2. Check for 120/240 Vac between the heat (W) and common (N)
terminals. If 120/240 Vac is present, the thermostat is functional.
For TB8575A:
1. Check for 24 Vac at the equipment on the secondary side of the
transformer between power and common (terminals R and C).
2. Check for 24 Vac between the heat terminal (W) and transformer
common. If 24 Vac is present, the thermostat is functional.
If voltage is present, check the heating equipment to find the cause of the
problem.
For TB6575A/B:
Check for 120/240 Vac between the heat (W) and common (N)
terminals.
For TB8575A:
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 that the Installer Setup code #2 (System Type) value matches the
installed heating and/or cooling equipment.
Separate the shorted heating and cooling wires.
14
TROUBLESHOOTING
Action