York YLUA0248 Series, Installation Operation & Maintenance

Page: 112 / 158

JOHNSON CONTROLS
112
FORM 150.73-NM2
ISSUE DATE: 09/07/2020
SECTION 7 – UNIT CONTROLS
cooling setpoint will be determined by a remote device
such as an ISN control. The message also indicates that
the control point is based on Discharge Air Tempera-
ture leaving the evaporator.
R E M O T E S U C T I O N
P R E S S U R E C O N T R O L
This message indicates that the cooling setpoint is un-
der REMOTE control. When under remote control, the
cooling setpoint will be determined by a remote device
such as an ISN control. This message also indicates
that the control point is based on Suction Pressure.
Immediately after the control mode message is dis-
played, the COOLING SETPOINT entry screen will be
displayed. If the unit is programmed for Discharge Air
Temperature the following message will be displayed:
S E T P O I N T = 5 5 . 0 ° F
R A N G E = + / - 5 . 0 ° F
(Discharge Air Temperature control)
The above message shows the current Discharge Air
temperature SETPOINT at 55.0°F (notice the cursor
positioned under the number 5). Pressing either the UP
or DOWN arrow will change the setpoint in .5°F incre-
ments. After using the UP and DOWN arrows to adjust
to the desired setpoint, the ENTER/ADV key must be
pressed to enter this number into memory and advance
to the RANGE SETPOINT.
This will be indicated by the cursor moving under the
RANGE setpoint. The UP and DOWN arrow keys are
used to set the RANGE, in .5 °F increments, to the de-
sired RANGE setpoint. After adjusting the setpoint, the
ENTER/ADV key must be pressed to enter the data
into memory.
The Discharge Air temperature SETPOINT is pro-
grammed from 45°F to 70°F. The Control Range is
programmed from 3.0°F to 10°F.
If the unit was programmed for Suction Pressure con-
trol, the following message would be displayed instead
of the previous message.
S Y S X S P = 1 0 5 __ P S I G
R A N G E = + / - 5 P S I G
(Suction Pressure control)
The setpoint and range are programmed with the UP
arrow. DOWN arrow, and ENTER/ADV key as de-
scribed in the previous setpoint message. The setpoints
in Suction Pressure Control are the suction pressures
of each individual system on the condensing Unit and
will control to /- the cooling range.
On two system units, each system is controlled inde-
pendently of each other according to its own setpoint
and cooling range, so there will be two similar displays
- a setpoint and range for both system 1 and system 2.
The Suction Pressure SETPOINTS are programmable
from 60 PSIG to 90 PSIG. The Control Range is pro-
grammable from 2 PSIG to 10 PSIG.
Both Discharge Air Temperature and Suction Pressure
control are described in detail under the section on Ca-
pacity Control.
Pressing the COOLING SETPOINTS again, after set-
ting the “local” setpoint(s), will display the remote set-
point and cooling range. This display automatically up-
dates about every 2 seconds. Notice that these setpoints
are not “locally” programmable, but are controlled by a
remote device such as an ISN control. These setpoints
would only be valid if the unit was operating in the
REMOTE mode. The following messages illustrate
both Discharge Air Temperature and Suction Pressure
control respectively.
R E M S E T P = 5 5 . 0 ° F
R A N G E = + / - 5 . 0 ° F
(Discharge Air Temperature control)
R E M S P X = 7 0 P S I G
R A N G E = + / - 3 P S I G
(Suction Pressure control)
Pressing the COOLING SETPOINTS again will bring
up the display that allows the Maximum EMS-PWM
Temperature Reset to be programmed. This message is
shown below.
M A X E M S - P W M R E M O T E
T E M P R E S E T = + 2 0 ° F
The Temp Reset value is the maximum allowable reset
of the Discharge Air Temperature Setpoint. The set-
point can be reset upwards by the use of a contact clo-
sure on the PWM Temp Reset input (XTBC1 terminals
13 - 20). See the section on Operating Controls for a
detailed explanation of this feature.