York MILLENNIUM Y22, Installation Manual

Page: 97 / 140

102777-YIM-E-0206
Unitary Products Group 97
modes are protected against frequent cycling, slugging, mul-
tiple restarts, etc.
One result is that the system may not immediately respond
as you expect. For example, internal digital timers may delay
the start of a compressor even though the thermostat calls for
cooling. The control may be in the middle of a timing
sequence; without the observer knowing what has already
happened and the status of current inputs, the system may
take action not expected by the tech.
In the Simplicity control, there are:
• a list of user-selected option settings and setpoints
recorded within the control;
• inputs monitored by the Simplicity;
• specific fixed rules and timings built in to the control
• outputs to compressors, heat, economizers, and
other options.
The Simplicity has a real-time clock function, with minimum of
ten hours ‘Time-of-day retention’ with unit power off.
The Millennium Simplicity control is resistor-configured for
Constant Volume (CV) units or Variable Air Volume (VAV)
units. The option settings for a specific option configuration
will be made as part of unit test at the factory; however, if
there is doubt about how a unit is responding in the field,
check the option setting for the unexplained action.
If connected to a network, the control requests an address by
a press of the Address/Down button.
DIAGNOSTICS VIA LED
There is an LED on the board that shows the status of the
control and alarms (see Status LED Table). There are two
character displays, one 2-digit and one 4-digit, to indicate
details of run conditions and alarms (see Alarms Table
in the
Trouble Shooting section of this manual).
When the Alarm / Change Data button (See Figure 2 Simplic-
ity Controller Push Buttons)
is pushed and released one time
within five seconds, it will re-enunciate the last five alarms on
the Display.
When this button is pushed and released two times within five
seconds, it will clear all stored alarms.
The error details for most conditions are stored in summary in
the Simplicity Control and can be accessed by the digital dis-
play, personal computer interface, or Palm Pilot (Some inter-
faces still in development).
Diagnosing requires patience because of internal timings.
Normal observable conditions are the same - contactor 1M
pulled in, compressor 1 running - but the control does not
identify what it has just done or is about to do. The Simplicity
control will take action according to its internal rules even
though action requests come from smart thermostats. A call
for cooling, for example, will be compared with supply air
temperature before energizing a cooling stage.
ERROR HISTORY
The Simplicity control stores up to 5 of the most recent
alarms in a First In, First Out (FIFO) manner. As the control
collects alarms, it will overwrite the oldest alarm after the his-
tory buffer becomes full.
Some system errors will initiate a controlling response as well
as being stored in the error memory buffer. See the “Trouble-
shooting” chapter in this manual for a detailed description of
how controller errors are handled.
Data items stored for maintenance / run history, in addition to
Alarms:
• Accumulated run times for each compressor and
heat stage
FIGURE 31 -SIMPLICITY CONTROLLER
FIGURE 32 -SIMPLICITY CONTROLS PUSH
BUTTONS
Program
Alarms / Change Data Address / Down
Test / Reset / Up