York YLAA0195HE, Manual, Page: 150 / 206

JOHNSON CONTROLS
150
FORM 150.72-NM3 (1020)
ISSUE DATE 10/05/2020
SECTION 7 – UNIT CONTROLS
See the “ Service And Troubleshooting ”
section of this IOM for Printer Installa -
tion information.
History Displays
The HISTORY key gives the user access to many unit
and system operating parameters at the time of a unit
or system safety shutdown. When the HISTORY key is
pressed the following message is displayed.
D I S P L A Y S A F E T Y S H U T-
D O W N N O . 1 ( 1 T O 9 )
While this message is displayed, the ↑ (UP) arrow key
can be used to select any of the six history buffers. Buffer
number 1 is the most recent, and buffer number 6 is the
oldest safety shutdown that was saved.
After selecting the shutdown number, pressing the
ENTER key displays the following message which
shows when the shutdown occurred.
S H U T D O W N O C C U R R E D
0 3 : 5 6 P M 2 9 J A N 0 2
The ↑ (UP) and ↓ (DOWN) arrow keys are used to scroll
forward and backward through the history buffer to
display the shutdown conditions stored at the instant the
fault occurred. The ↓ (DOWN) arrow key scrolls through
the displays in the order they appear below:
U N I T F A U L T :
L O W L I Q U I D T E M P
Displays the type of fault that occurred.
U N I T T Y P E
L I Q U I D C H I L L E R
Displays the type of chiller; Liquid, Condensing Unit
or Heat Pump.
C H I L L E D L I Q U I D
X X X X X
Displays the chilled liquid type; Water or Glycol.
A M B I E N T C O N T R O L
X X X X X X X X X X
Displays the type of Ambient Control; Standard or Low
Ambient.
L O C A L / R E M O T E M O D E
X X X X X X X X X
Displays Local or Remote control selection.
History Printout
Pressing the PRINT key and then the HISTORY key
allows the operator to obtain a printout of information
relating to the last 9 Safety Shutdowns which occurred.
The information is stored at the instant of the fault,
regardless of whether the fault caused a lockout to
occur. The information is also not affected by power
failures (long-term internal memory battery backup
is built into the circuit board) or manual resetting of a
fault lock-out.
When the HISTORY key is pressed, a printout is
transmitted of all system operating conditions which
were stored at the “instant the fault occurred” for each of
the 9 Safety Shutdowns buffers. The printout will begin
with the most recent fault which occurred. The most
recent fault will always be stored as Safety Shutdown
No. 1. identically formatted fault information will then
be printed for the remaining safety shutdowns.
Information contained in the Safety Shutdown buffers is
very important when attempting to troubleshoot a system
problem. This data reflects the system conditions at the
instant the fault occurred and often reveals other system
conditions which actually caused the safety threshold
to be exceeded.
The history printout is similar to the operational data
printout shown in the previous section. The differences
are in the header and the schedule information. The daily
schedule is not printed in a history print.
The following is one example of a history buffer printout.
The data part of the printout will be exactly the same as
the operational data print so it is not repeated here. The
difference is that the Daily Schedule is not printed in the
history print and the header will be as follows.
YORK INTERNATIONAL CORPORATION
MILLENNIUM LIQUID CHILLER
SAFETY SHUTDOWN NUMBER 1
SHUTDOWN @ 3:56PM 01 AUG 09
SYS 1 HIGH DSCH PRESS SHUTDOWN
SYS 2 NO FAULTS