York J Series - Sequence of Operation

FORM 100.50-NOM7 (808)
17
JOHNSON CONTROLS
3
SECTION 3 – SEQUENCE OF OPERATION
COMPRESSOR STAGING
Constant Volume and Variable Air Volume stage com-
pressors as follows:
Note that ASCD (anti short cycle delay) and Minimum
Run Time will take priority above Compressor total-
ized run time. For example, when turning on the rst
stage, the control will determine which compressor
has the shortest total run time and also read the ASCD
timers for each compressor. If the compressor with the
shortest total run time has expired, it’s ASCD, then that
compressor will be started. If the compressor with the
shortest total run time has not expired, it’s ASCD but
the other compressor has, then the compressor with the
longer run time will be started.
The OptiLogic™ controller has default programming for either 4 or 6 stages of cooling.
The R410A units are all 4 compressor, thus program for 4 cooling stages.
TABLE 1 - 25 – 40-TON R410A COMPRESSOR LOGIC
Compressor Logic Constant Volume VAV
1 Compressor 1 Compressor 1
2
Compressor 2 Compressor
3 or 4
3
Compressor
3 or 4
Compressor
2, 3 or 4
4
Compressor
4 or 3
Compressor
2, 3 or 4