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YORK INTERNATIONAL
91
FORM 150.62-NM1
LOW AMBIENT CONDENSER FAN CONTROL
For unit operation below 25°F (-3.9°C) a low ambient
kit is required. The kit consists of a discharge pressure
transducer(s) and reversing contactors.
With the low ambient kit installed and the unit pro-
grammed for low ambient operation, the condenser fans
will operate as shown in Tables 41 and 42.
TABLE 41 – LOW AMBIENT CONDENSER FAN CONTROL – AMBIENT TEMPERATURE AND DISCHARGE
PRESSURE CONTROL
Again, notice that condenser fan operation can be pro-
grammed for either “temperature and discharge pres-
sure control,” or “discharge pressure control only” as
described under Condenser Fan Control.
The fan control on-pressure (ctrl_press) and the fan def-
erential off-pressure (diff_press) are programmable un-
der the PROGRAM key.
TABLE 42 – LOW AMBIENT CONDENSER FAN CONTROL – DISCHARGE PRESSURE CONTROL
2
FAN STAGE ON OFF
1
OAT >25° F (-3.9°C) OAT < 20° F (-6.7°C)
1 FAN REV
OR AND
DP > ctrl_press DP < ctrl_press - diff_press
2
OAT >45°F (7.2°C) OAT < 40°F (-4.40°C)
1 FAN FWD
OR AND
DP > ctrl_press + 20 PSIG (1.38 Bars) DP < ctrl_press - diff_press + 20 PSIG (1.38 Bars)
3
OAT > 65°F (18.3°C) OAT < 60°F (15.6°C)
2 FANS FWD
OR AND
DP > ctrl_press + 40 PSIG (2.76 Bars) DP < ctrl_press - diff_press + 40 PSIG (2.76 Bars)
FAN STAGE ON OFF
1
1 FAN REV DP > ctrl_press DP < ctrl_press - diff_press
2
1 FAN FWD DP > ctrl_press + 20 PSIG (1.38 Bars) DP < ctrl_press - diff_press + 20 PSIG (1.38 Bars)
3
2 FANS FWD DP > ctrl_press + 40 PSIG (2.76 Bars) DP < ctrl_press - diff_press + 40 PSIG (2.76 Bars)