Troubleshooting A Millennium; Simplicity® Control; Status Led Chart; Failure Modes And Default Operation - York MILLENIUM SIMPLICITY ELITE Series Technical Application And Programming Manual

TROUBLESHOOTING A MILLENNIUM

®
CONTROL
Simplicity

STATUS LED CHART

The Status LED mounted on the controller PC board will flash
specified flash patterns to indicate rooftop unit status. See Table
14.
Table 14: Status Led Chart
Flash Codes
On Steady Control Failure
1 Flash (Not Applicable)
2 Flashes Control waiting ASCD
OFF No Power or Control Failure
Flash Times:
• Off: The power is Off, or the control has failed
• On 250ms Off 250ms: The Control is operating but an
Alarm is active.
• (The Number of the Alarm will be displayed on the charac-
ter display.)
• On one second, Off one second: This will be the "Heat
Beat"; The Control is operating normally with no Alarms.
• On Steady: The Control has Failed
• Two flashes On, then two seconds Off: The Control is
waiting for an ASCD Timer to finish.

FAILURE MODES AND DEFAULT OPERATION

ERROR HISTORIES
Error data storage: The control will store the latest five errors in a
FIFO manner in EEPROM, for later display. It will store status
information ("active" vs. "inactive") for all error types to provide
for situations when an error snapshot is triggered by multiple
errors occurring at the same time. As the control collects errors, it
will overwrite the oldest error after the history buffer becomes full.
Errors that are entered into the error history buffer:
• Compressor locked out on safety chain trip
• Supply fan failure
• Heating SAT failure
• Cooling SAT failure
• SAT,RAT,OAT,IAQ, ST, or RH failure
• Duct static or Bldg. Pressure sensor failure
• Dirty Filter alarm
• High duct static alarm
• Hot Water Coil Freeze alarm
• External alarm input
• Bad Air Proving Switch
Johnson Controls Unitary Products
®
Description

SENSOR FAILURES AND DEFAULT OPERATION

A failure of SAT RAT, OAT, IAQ, Space Temperature, or an outside
or return air Relative Humidity sensor will generate a common
error. A failure of the Duct Static or Building Pressure sensor will
generate another common error. The errors will be indicated by a
Status LED (see Status LED Chart earlier in this chapter). The
errors will be written to the Error History Buffer. In networked
application, the error flag will be readable by the network. The error
indication of a sensor failure will continue until the problem is
corrected and will automatically terminate when the sensor is
again detected as reliable. If the unit is shut down as a result of a
sensor failure, the alarm must be reset (after the sensor problem
has been corrected) by resetting the controller (power cycle, or
reset command issued by the Palm Pilot Configuration Tool).
SAT SENSOR
CV operation: If the SAT sensor fails, the Economizer,
excessive SAT control and predicted SAT drop checking will be
disabled. The Control will then continue a "limp along" operation
under zone thermostat, or zone sensor control. For VAV
operation the unit will be shut down.
RAT SENSOR
If the RAT sensor fails, Morning Warm Up mode and VAV
Occupied Heating are disabled. For Economizer Loading
function, the control will default to estimated RAT of 75 °F (for
this function only).
OAT SENSOR
Units without Economizer: If there is no Economizer, the
control will lockout Cooling on an OAT sensor failure. This is
because the controller can not determine when cooling needs
to be locked out at low OAT to prevent damage to compressors.
Heating operation will continue normally.
Units with Economizer: All Economizer Operation will be
disabled. This is because OAT sensor is the most essential sensor
in determining availability of free cooling. Even if the unit is
equipped with Outside RH sensor and controller could calculate
Outdoor Enthalpy, the OAT sensor is still essential in that
calculation. The Economizer will only modulate to the Minimum
Position when the Fan is operating and the control is Occupied.
OUTSIDE AIR RELATIVE HUMIDITY SENSOR
If the OAH sensor fails, the control will only use the OAT sensor
to decide if Free Cooling is available. The control will self-
configure to Outside Temperature Method (see also
Economizer Operation section earlier in this document).
RETURN AIR RELATIVE HUMIDITY SENSOR
The control will self-configure to Outside Enthalpy Operation.
SPACE TEMPERATURE SENSOR
CV operation with a zone sensor: When this sensor fails the
control will see if it has a RAT sensor. If it has a RAT sensor, the
control will use it as a backup and continue temperature control
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