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field wired to CTB1 terminals 13 to 16. CTB 1 terminal is
located in the control panel. Refer to Figure 5 and unit
wiring diagram.
See Air Proving Switch and Remote Start-
Stop Contacts sections below.
Suction Pressure Control cannot be used unless the
optional suction transducers are installed on the unit
(standard on YCUL0211 - YCUL0275).
Suction Temperature Sensors (optional)
This is a field installed option that provides individual
displays of suction line temperature for each system at
the condensing unit. This option performs no control func-
tion, but simply provides the suction line temperature for
each refrigerant system as measured at the condensing
unit.
On the microboard, the connections are field wired to
J5, pins 7, 12, & 1 for System 1; J5, pins 8,13 & 2 for
System 2. Refer to Figure 9 and unit wiring diagram.
The sensors should be attached to the suction line with
copper straps, and heat conducting compound should
be used to ensure good heat transfer.
Air Proving Switch
The air proving switch is field wired to CTB1 terminals 13
to 14 to prevent operation of the refrigerant circuit when
the supply air blower is not operating.
If separate evaporator blowers are used with respect to
each refrigerant system in the condensing unit, then two
air proving switches must be wired in series across CTB1
terminals 13 - 14 (one for each evaporator blower). Refer
to Figure 5 and unit wiring diagram.
When using Zone Thermostats in Suction Pressure Con-
trol mode, the air proving switch(es) should be wired in
series with the respective Zone Thermostats.
Remote Start/Stop Contacts
To remotely start and stop the condensing unit, dry con-
tacts can be wired in series with the air proving switch
and CTB1 - terminals 13 to 14. Refer to Figure 5 and unit
wiring diagram.
Remote Emergency Cutoff
Immediate shutdown of the condensing unit can be ac-
complished by opening a field installed dry contact to
break the electrical circuit between terminals 5 to L on
terminal block CTB2. CTB2 is located in the power panel.
YORK INTERNATIONAL
The unit is shipped with a factory jumper installed be-
tween terminals 5 to L, which must be removed if emer-
gency shutdown contacts are installed. Refer to Figure
6 and unit wiring diagram.
Evaporator Blower Start Contacts
For constant fan operation: Terminal block CTB2 - termi-
nals 23 to 24, are normally open contacts that can be
used to switch field supplied power to provide a start
signal to the evaporator blower contactor.
Refer to Figure 6 and unit wiring diagram.
Compressor Run Contacts
Contacts are available to monitor "Compressor Run" sta-
tus. Normally-open auxiliary contacts from each com-
pressor contactor are wired in parallel with CTB2 - termi-
nals 25 to 26 for system 1, and CTB2 - terminals 27 to
28 for system 2 (YCUL0125 - YCUL0275). Refer to Fig-
ure 6 and unit wiring diagram.
Alarm Status Contacts
Normally-open contacts are available for each refriger-
ant system. These normally-open contacts close when
the system is functioning normally. The respective con-
tacts will open when the unit is shut down on a unit fault,
or locked out on a system fault. Field connections are at
CTB2 terminals 29 to 30 (system 1), and terminals 31 to
32 (system 2). Refer to 6 and unit wiring diagram.
PWM Input
The PWM input allows reset of the discharge air tem-
perature setpoint (when unit is programmed for Discharge
Air Temperature Control mode) by supplying a "timed"
contact closure. Field wiring should be connected to
CTB1 - terminals 13 to 20. A detailed explanation is pro-
vided in the Unit Control section. Refer to Figure 5 and
unit wiring diagram.
Load Limit Input
Load limiting is a feature that prevents the unit from loading
beyond a desired value. The unit can be "load limited"
either 33%, 50%, or 66%, depending on the number of
compressors on the unit. The field connections are wired
to CTB1- terminals 13 to 21, and work in conjunction
with the PWM inputs. A detailed explanation is provided
in the Unit Control section. Refer to Figure 5 and unit
wiring diagram.
When using the Load Limit feature, the
PWM feature will not function - SIMUL-
TANEOUS OPERATION OF LOAD LIMIT-
ING AND TEMPERATURE RESET (PWM
INPUT) CANNOT BE DONE.
FORM 150.63-NM2
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