76
YORK INTERNATIONAL
Programming
The control panel may be programmed for AMBIENT &
DISCH PR FAN CONTROL (Ambient & discharge pres-
sure fan control) or by DISCHARGE PRESSURE FAN
CONTROL (fan control by discharge pressure only).
This is selected by placing SW. 8 on the microprocessor
to the appropriate position. See page 29.
SW. 2 on the Microprocessor Board must also be pro-
grammed for LOW AMBIENT CONTROL to allow op-
eration at temperatures below 25°F. To accomplish this,
place SW. 2 in the CLOSED position. See page 28. After
the switch is properly positioned, the OUTSIDE AIR TMP
LOW CUT-OUT in the PROGRAM mode can then be
programmed between 0° - 25°F. See page 35.
NOTE: For operation below 0°F, program the cut-out for
0°F. This will cause the microprocessor to
ignore the low ambient cut-out regardless of
temperature.
Operation of the fans will be discussed in both Ambient
and Pressure Control as well as Pressure Only control
in the following text.
Ambient and Pressure Fan Control
0°F - 25°F
Fan operation on each system below 25°F is controlled
only by the discharge pressure of the respective system.
Each system will operate 4 steps of fan control as fol-
lows:
1. Until discharge pressure reaches 320 PSIG, the
fans will be completely off.
2. The second stage of fan control will energize fan 1
(SYS 1, 7M) or fan 3 (SYS 2, 10M) in the reverse
direction when the discharge pressure exceeds 320
PSIG. Once the reversing contactor is energized, it
will stay on until the discharge pressure of the sys-
tem falls below 120 PSIG, the ambient temperature
exceeds 35°F, or discharge pressure of the system
rises above 340 PSIG.
NOTE: The corresponding compressor must be on
for a minimum of 4 seconds before the re-
versing fans are permitted to start.
3. The third stage of fan control will energize fan 2 (SYS
1, 6M) or fan 4 (SYS 2, 9M) as well as turn off the
reversing fans on the respective system whenever
discharge pressure exceeds 340 PSIG. These fans
will stay on until discharge pressure drops below
120 PSIG.
NOTE: The corresponding compressor must be on
for 4 seconds before these fans are permit-
ted to start.
4. The fourth stage of fan control will energize fan 1
(SYS 1, 5M) or fan 3 (SYS 2, 8M) and will operate
the corresponding fans in the forward direction when-
ever discharge pressure exceeds 360 PSIG. These
fans will stay on until discharge pressure drops be-
low 140 PSIG.
NOTE: The corresponding compressor must be on
for 4 seconds before these fans are permit-
ted to start.
Ambient and Pressure Fan Control
25° - 45°F
Fan control between 25° 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 pressure 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 compressor op-
eration fan 2 or 4 (SYS 1 ) or 7 & 8 (SYS 2) will ener-
gize. This is identical to standard fan control by tempera-
ture (Page 67). No pressure override exists. If tempera-
ture drops below 25°F, these fans will remain on until
cycled off by pressure.
Ambient and Pressure Fan Control
50°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 67). This fan will de-ener-
gize 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.
Summary of Contents for YCAZ88EE8
Page 16: ...16 YORK INTERNATIONAL WIRING DIAGRAMS LD02165 FIG 5 ELEMENTARY DIAGRAM ...
Page 17: ...FORM 150 60 NM3 17 YORK INTERNATIONAL FIG 5 ELEMENTARY DIAGRAM Cont d LD02166 ...
Page 20: ...20 YORK INTERNATIONAL CONNECTION DIAGRAM ELECTRICAL BOX FIG 7 CONNECTION DIAGRAM LD02171 ...
Page 21: ...FORM 150 60 NM3 21 YORK INTERNATIONAL FIG 7 CONNECTION DIAGRAM Cont d LD02172 ...