78
YORK INTERNATIONAL
Ambient and Pressure Fan Control
25° - 45°F
Fan control between 25°F and 35°F is controlled by dis-
charge pressure. If the reversing fans are on, the revers-
ing fan will continue to operate until the temperature
reaches 35°F or discharge temperature reaches 340
PSIG. At 35°F or 340 PSIG, fan 2 (SYS 1, 6M) or fan 4
(SYS 2, 9M) will energize. Between 25°F and 45°F if the
reversing fan is not operating, after 4 seconds of com-
pressor operation fan 2 or 4 (SYS 1) or 7 and 8 (SYS 2)
will energize. This is identical to standard fan control by
temperature (page 68). No pressure override exists. If
temperature drops below 25°F, these fans will remain on
until cycled off by pressure.
Ambient and Pressure Fan Control
45°F and Higher
Fan control above 45°F is strictly controlled by tempera-
ture with no pressure override.
After 4 seconds of operation, fan 2 (SYS 1, 6M) or fan 4
(SYS 2, 9M) will energize turning the fan in the forward
direction.
After 30 seconds of operation, fan 1 (SYS 1, 5M) or fan
3 (SYS 2, 8M) will energize turning an additional fan on
in the forward direction. This is identical to standard fan
control by temperature (Page 66). This fan will
de-energize if ambient temperature drops below 40°F.
Pressure Control Only,
Fan Control by Discharge Pressure
Fan control by pressure will operate 4 stages of fan cy-
cling according to the discharge pressure of the cor-
responding system. Ambient temperature will have no
effect.
1. Until discharge pressure reaches 320 PSIG, no sys-
tem fans will operate.
2. When discharge pressure of either system reaches
320 PSIG fan 1 (SYS 1, 7M) or fan 3 (SYS 2, 10M)
will be energized in the reverse direction. This fan will
remain energized until discharge pressure of either
system drops below 120 PSIG.
3. If discharge pressure of either system reaches 340
PSIG, the reversing fans on the respective system
will be turned off. At the same time, fan 2 (SYS 1,
6M) or fan 4 (SYS 2, 9M) will energize. This fan will
remain on until discharge pressure of either system
drops below 120 PSIG.
4. If discharge pressure of either system reaches 360
PSIG and compressor run time has exceeded 30 sec-
onds, fan 1 (SYS 1, 5M) or fan 3 (SYS 2, 8M) will
energize turning the fan in the forward direction. This
fan will remain on until discharge pressure of either
system drops to 140 PSIG.
Table 2 shows the operation of both modes of fan control
previously discussed.
TABLE 2
LOW AMBIENT FAN CYCLING
CONTROL BY
CONTROL BY
TEMPERATURE & PRESSURE
PRESSURE ONLY
SYS
FAN
CONTACTOR
BELOW 25°F PRESSURE
ABOVE 25°F TEMPERATURE
TEMPERATURE
CONTROL ONLY
CONTROL ONLY
HAS NO EFFECT
ON
OFF
ON
OFF
ON
OFF
1 REV
7M
320 PSIG
120 PSIG
Will Not Start
35°F or
320 PSIG
120 PSIG
Above 25°F
340 PSIG
Turns OFF by
1
2
6M
340 PSIG
120 PSIG
25°F
Pressure
340 PSIG
120 PSIG
Only at
120 PSIG
1 FWD
5M
360 PSIG
140 PSIG
45°F
40°F
360 PSIG
140 PSIG
3 REV
10M
320 PSIG
120 PSIG
Will Not Start
35°F or
320 PSIG
120 PSIG
Above 25°F
340 PSIG
Turns OFF by
2
4
9M
340 PSIG
120 PSIG
25°F
Pressure
320 PSIG
120 PSIG
Only at
120 PSIG
3 FWD
8M
360 PSIG
140 PSIG
45°F
40°F
360 PSIG
140 PSIG
NOTE: Fans with reversing contactors will have the reversing contactors mechanically locked out when the fans are running forward. The
forward contactor will also be locked out when the fans are running in reverse.