York MILLENIUM YCAS Series, Installation Operation & Maintenance, Page: 142 / 156

142
YORK INTERNATIONAL
MOTOR
TERMINAL BOX
(TYP.)
LD05908
Micro Panel Contents
8.4 CONDENSER FAN CONTROL
The chiller is equipped with 6 condenser fans, with 3
fans per system as shown in Fig. 42 below. Fan control
is via Outside Ambient Temperature (OAT) and Dis-
charge Pressure (DP). There are 3 or 6 stages of fan
control, depending upon the version of EPROM, utiliz-
ing 3 outputs per system from the Relay Output Board.
The fan stages will operate according to Tables 3, 4, 5
and 6, according to the EPROM version installed. Op-
eration of the fans, regardless of the EPROM ver-
sion, will be satisfactory in all ambient conditions,
Tables are provided which show fan on/off points and
also include fan contactors, wire numbers, and Relay
Output Board output numbers related to specific fans
operation. System 1 fan contactors are controlled by
Relay Output Board #1 and System 2 fan contactors
are controlled by Relay Output Board #2.
are met. For example, if a system is at fan stage 4, and the
DP falls below 13.4 BARG and the OAT drops below
23.9 °C, the fan stage will be reduced to stage 3.
EPROM Version C.A17.09.02 (5320)
Fan operation on these versions is outlined in Table 5.
These EPROM versions operate very similar to ver-
sions 0 and 1. The only difference is that the ON/OFF
pressures are 1.0 BARG lower. Condenser fan ON con-
ditions are governed solely by the Discharge Pressure
(DP). When the DP rises above 14.1 BARG, fan stage
1 is activated. From there, subsequent fan stages are
activated as the discharge pressure rises in increments
of 1.0 BARG, except stage 6, which is activated when
the DP rises over 19.0 BARG. The system will remain
at the highest fan stage reached unless the OFF condi-
tions outlined in the next paragraph are satisfied.
Condenser fan OFF conditions are governed by both the
DP and OAT. Fan staging will be decreased from the highest
fan stage reached if both the DP and OAT requirements
are met. For example, if a system is at fan stage 4, and the
DP falls below 12.4 BARG and the OAT drops below
23.9°C, the fan stage will be reduced to stage 3.
EPROM Versions C.A32.09.02 (0483),
C.ACS.09.02 (D87E), and C.A06.09.03 (E10C)
These EPROM’s operate according to the Flowchart in
Fig. 42. This control scheme is designed to minimize fan
cycling. Whenever discharge pressure stabilizes be-
tween 10.3 BARG and 17.2 BARG, the micro will nei-
ther start or stop stages of fans.
If discharge pressure rises between 17.2 BARG and
19.7 BARG, the micro will add another fan stage and
start a 15 minute timer. If the discharge pressure re-
mains in this range for 15 minutes, another step of fan
cycling will be added and the micro will restart the 15
minute timer.
If discharge pressure falls between 10.3 BARG and
8.3 BARG, a step of fan cycling will be dropped and the
micro will start a 15 minute timer. If the discharge pres-
sure remains in this range for 15 minutes, another step
of fan cycling will be dropped and the micro will restart
the 15 minute timer.
If discharge pressure rises above 17.2 BARG, the mi-
cro will add a step of fan cycling every 5 seconds, until
the discharge pressure drops below 17.2 BARG in an
effort to quickly control the discharge pressure to an
acceptable range.
FIG. 41 – CONDENSER FAN CONTROL LAYOUT
FOR DXST COMPRESSORS UNITS
EPROM Versions C.ACS.09.01 (F350)
and C.ACS.09.02 (3902)
Fan operation on these versions is outlined in Table 4.
Condenser fan ON conditions are governed solely by
the Discharge Pressure (DP). When the DP rises above
15.2 BARG, fan stage 1 is activated. From there, sub-
sequent fan stages are activated as the discharge pres-
sure rises in increments of 1.0 BARG, except stage 6,
which is activated when the DP rises over 20 BARG.
The system will remain at the highest fan stage reached
unless the OFF conditions outlined in the next paragraph
are satisfied.
Condenser fan OFF conditions are governed by both the
DP and OAT. Fan staging will be decreased from the highest
fan stage reached if both the DP and OAT requirements