Troubleshooting (Uc400) - Trane HUV Installation, Operation And Maintenance Manual

two seconds.The green LED will begin to blink, indicating
the controller is in test mode.
Table 47. Test sequence for 1-heat/1-cool configurations
(Tracer ZN520)
Fan
Steps BOP1-3
1. Off Off
2. Fan High High
3. Fan Medium Medium
4. Fan Low Low
5. Cool High
6. Heat High
(b)
7. Fresh Air Damper High
(c)
8. Exit
Note: For all 1-heat/1-cool applications including 2-pipe changeover, BOP4
energizes in the cooling test stage and BOP5 energizes in the heat
test stage.This occurs even though during normal 2-pipe changeover
operation BOP4 controls the unit valve for both cooling and heating.
(a) At the beginning of the Fan High step, the controller attempts to clear
all diagnostics.
(b) The fresh air damper (BOP6) only energizes during this step if binary
output 6 has been configured as a fresh air damper.
(c) After the Fresh Air Damper step, the test sequence performs the Exit
step.This initiates a reset and attempts to return the controller to normal
operation.
UV-SVN02C-EN
Cool Heat
Output Output Damper
(a)
BOP4 BOP5 BOP6
Off Off Closed
Off Off Closed
Off Off Closed
Off Off Closed
On Off Closed
Off On Closed
Off Off Open

Troubleshooting (UC400)

Table 48 through Table 53, p. 103
information if encountering operational problems with the
UC400 controller.
Table 48. Fan does not energize (UC400)
Probable
Cause Explanation
Unit wiring The wiring between the controller outputs and the fan
relays and contacts must be present and correct for normal
fan operation. Refer to applicable wiring diagram.
Failed end The fan motor and relay must be checked to ensure proper
device operation.
Normal The fan will turn OFF when:
operation • The controller receives a communicated off signal
• The fan-speed switch is set to OFF if no communicated
value is present
• Specific diagnostics are generated
• The default fan speed is set to OFF and the fan is
operating in the Auto mode.
If the controller is in unoccupied mode, the fan cycles
between OFF and the highest fan speed.
No power to If the controller does not have power, the unit fan does not
the controller operate. For the controller to operate normally, it must
have an input voltage of 24 Vac. If the Marquee/Power LED
is OFF continuously, the controller does not have sufficient
power or has failed.
Diagnostic Several diagnostics affect fan operation. For detailed
present information about these diagnostics, refer to
p. 93.
Unit The controller must be properly configured based on the
configuration actual installed end devices and application. If the unit
configuration does not match the actual end device, the
fans may not work correctly.
Random start After power-up, the controller always observes a random
observed start from 5 to 30 seconds. The controller remains OFF
until the random start time expires.
Cycling fan The controller continuously operates the fan when in the
operation/ occupied, occupied standby, or occupied bypass mode.
continuous When the controller is in the unoccupied mode, the fan is
cycled between high speed and OFF with capacity.
Unoccupied Even if the controller is configured for continuous fan
operation operation, the fan normally cycles with capacity during
unoccupied mode. While unoccupied, the fan cycles ON or
OFF with heating/cooling to provide varying amounts of
heating or cooling to the space.
Fan mode off If a local fan mode switch determines the fan operation, the
OFF position controls the fan to off.
Requested The user can communicate a desired operating mode (such
mode off as OFF, heat, and cool) to the controller. If OFF is
communicated to the controller, the unit controls the fan to
off. There is no heating or cooling.
Table 49. Valves remain closed (UC400)
Probable
Cause Explanation
Unit wiring The wiring between the controller outputs and the valve(s)
must be present and correct for normal valve operation.
Refer to applicable wiring diagram.
Failed end The valves must be checked to ensure proper operation.
device
No power to If the controller does not have power, the unit valve(s) will
the controller not operate. For the controller to operate normally, apply
an input voltage of 24 Vac. If the Marquee/Power LED is
OFF continuously, the controller does not have sufficient
power or has failed.
Diagnostic Several diagnostics affect valve operation. For detailed
present information about these diagnostics, refer to
p. 93.
Normal The controller opens and closes the valves to meet the unit
operation capacity requirements.
Diagnostics
provide troubleshooting
Table 37,
Table 37,
101