York YCUL0020, Installation, Operation And Maintenance Manual

Page: 128 / 178

JOHNSON CONTROLS
128
Form 150.63-NM9
Issue date: 5/20/2021
SECTION 7 – UNIT CONTROLS
The low limit, high limit, and default values for the
keys under “SETPOINTS” are listed in Table 14 .
Schedule/Advance Day key
The SCHEDULE is a seven day daily schedule that al-
lows one start/stop time each day. The schedule can
be programmed Monday through Sunday with an al-
ternate holiday schedule available. If no start/stop
times are programmed, the unit will run on demand,
providing the unit is not shut off on a unit or system
shutdown. The daily schedule is considered “not pro-
grammed” when the times in the schedule are all zeros
(00:00 AM).
To set the schedule, press the SCHEDULE/ADVANCE
DAY key. The display will immediately show the fol-
lowing display.
M O N S T A R T = 0 0 : 0 0 A M
S T O P = 0 0 : 0 0 A M
The line under the 0 is the cursor. It may be changed
by using the ↑ (UP) and ↓ (DOWN) arrow keys until
correct. Pressing the ENTER/ADV key will enter the
times and then move the cursor to the minute box. The
operation is then repeated if necessary. This process
may be followed until the hour, minutes, and meridian
(AM or PM) of both the START and STOP points are
set. After changing the meridian of the stop time, press-
ing the ENTER/ADV key will advance the schedule to
the next day.
Whenever the daily schedule is changed
for Monday, all the other days will change
to the new Monday schedule. This means
if the Monday times are not applicable
for the whole week then the exceptional
days would need to be reprogrammed to
the desired schedule.
To page to a specific day press the SCHEDULE/AD-
VANCE DAY key. The start and stop time of each day
may be programmed differently using the ↑ (UP) and ↓
(DOWN) arrow, and ENTER/ADV keys.
After SUN (Sunday) schedule appears on the display
a subsequent press of the SCHEDULE/ADVANCE
DAY key will display the Holiday schedule. This is a
two part display. The first reads:
H O L S T A R T = 0 0 : 0 0 A M
S T O P = 0 0 : 0 0 A M
The times may be set using the same procedure as de-
scribed above for the days of the week. After chang-
ing the meridian of the stop time, pressing the ENTER/
ADV key will advance the schedule to the following
display:
S _ M T W T F S
H O L I D A Y N O T E D B Y *
The line below the empty space next to the S is the
cursor and will move to the next empty space when
the ENTER/ADV key is pressed. To set the Holiday,
the cursor is moved to the space following the day of
the week of the holiday and the ↑ (UP) arrow key is
pressed. An * will appear in the space signifying that
day as a holiday. The * can be removed by pressing the
↓ (DOWN) arrow key.
The Holiday schedule must be programmed weekly.
Once the holiday schedule runs, it will revert to the
normal daily schedule.
Program key
There are ten operating parameters under the PRO-
GRAM key that are programmable. These setpoints
can be changed by pressing the PROGRAM key, and
then the ENTER/ADV key to enter
Program Mode
.
Continuing to press the ENTER/ADV key will display
each operating parameter. While a particular parameter
is being displayed, the ↑ (UP) and ↓ (DOWN) arrow
keys can be used to change the value. After the value
is changed, the ENTER/ADV key must be pressed to
enter the data into memory. Table 15 shows the pro-
grammable limits and default values for each operating
parameter.
The following are the displays for the programmable
values in the order they appear:
d
D I S C H A R G E P R E S S U R E
C U T O U T = 5 7 0 P S I G
DISCHARGE PRESSURE CUTOUT is the discharge
pressure at which the system will shutdown as moni-
tored by the optional discharge transducer. This is a
software shutdown that acts as a backup for the me-
chanical high pressure switch located in the refrigerant
circuit. The system can restart when the discharge pres-
sure drops 40 psig (2.76 barg) below the cutout point.