YORK INTERNATIONAL
57
FORM 150.40-NM25
Unit Start-Up Sequence
A simplified start-up sequence is provided on the con-
trol panel to aid the operator in running the chiller.
SYS 1 and SYS 2 “ON/OFF” Switches
These switches allow the operator to manually turn ei-
ther system on or off. To operate a system, the respec-
tive switch must be in the “ON” position.
“SYS 1 LEAD/LAG’’ Select
This switch allows the operator to select SYS 1 as the
DUAL CIRCUIT UNITS
START/STOP AND LEAD/LAG CONTROLS
Before attempting start-up, the temperature and start/stop controls should be properly set and understood.
FIG. 40 – START/STOP & LEAD/LAG CONTROLS
lead or lag compressor if SW7 on the Micro Logic Board
is in the ON position (See Pages 66 and 67 for Micro
Logic Board Switch position.)
If SW7 on the Micro Logic Board is in the OFF position,
the Micro will try to balance run time between the two
compressors. The micro accumulates run time or both
systems as long as power is not interrupted to the con-
trol system. On a SYS 1 shutdown, run times on both
compressors are compared, and a decision is made as
to which system (system with least run time) is to be put
in the lead.
LD01869
