Trane Rtaaiom3 Manual

							101RTAA-IOM-3
Menu 2 - Service #2 Display
20 - Compressor Mode: The current
compressor operating status, as shown
in Figure 53, will be displayed when
this menu item is selected.
21 - Compressor Suction Rfgt.
Temperature: Temperature as read by
the suction temperature sensor (see
Figure 40).
22 - Saturated Evaporator Rfgt
Temperature: Temperature as read by
the saturated evaporator temperature
sensor (see Figure 40).
23 - Evaporator Refrigerant Pressure:
The pressure displayed is the
evaporator refrigerant temperature
converted to an R-22 pressure. Units
are PSIG (Kilopascal gauge), referenced
to sea level (14.6960 psia or 101.3289
KPa absolute).
24 - Saturated Condenser Rfgt
Temperature: Temperature as read by
the saturated condensing temperature
sensor (see Figure 40).
25 - Condenser Refrigerant Pressure:
The pressure displayed is the
condenser refrigerant temperature
converted to an R-22 pressure. Units
are PSIG (Kilopascal gauge), referenced
to sea level (14.6960 psia or 101.3289
KPa absolute).
26 - EXV Test: EXV test will be initiated
when the unit is in STOP/RESET and
EXV Test is set to the “Enable” mode.
See “Electronic Expansion Valve (EXV)
Test’. Mode will automatically be reset
to “disable” upon completion of the
test.
27 - Compressor % RLA: The
percentage of Rated Load Amps on the
highest leg of the compressor motor.
See discussion in “Current Overload
Protection”.
28 - % Line Volts (Optional): If the unit
is installed with the optional over/under
voltage transformer, the UCM will
display the percentage value of line
volts as based on the nominal line
voltage set in Menu 4, Item 45.29 - Compressor Starts (Optional): This
item serves as a non-resettable, non-
volatile accumulator of compressor
starts and is referenced by the UCM to
determine balancing of compressor
starts.
2A - Compressor Hours (Optional):
This item serves as a non-resettable,
non-volatile accumulator of
compressor hours and is referenced by
the UCM to determine balancing of
compressor hours.
2b - Compressor Test: Allows service
personnel to start a compressor and
check its operation. This eliminates the
time of waiting for the UCM lead/lag
function or load demand to start a
compressor. With the display indicating
the number of the circuit to be started,
change the display to “E” to start the
compressor on that circuit. After start,
the display will automatically return to
“d” and the UCM will resume its lead/
lag function of compressor control.
Menu 3 - Auxiliary Options
30 - External Chilled Water Setpoint:
Enables or disables chilled water
setpoint from an external control
system. See discussion in “Leaving
Chilled Water Temperature Control”.
31 - External Current Limit Setpoint:
Enables or disables current limit
setpoint for the system from an
external control system. See discussion
in “Current Limit Setpoint”.
32 - Ice Making Control: Enables or
disables the unit, when commanded by
a contact closure, to run fully loaded
and to stop, once ice termination
setpoint has been reached, e.g. ice
storage applications.
33 - Active Ice Termination Setpoint:
The selected temperature, from a
remote controller, such as a Tracer,
multiple-machine controller, or a
remote display panel, at which to
terminate the ice building mode, based
on the evaporator entering water
temperature. If no remote controllers
are connected, this setpoint should
agree with the Front Panel ice
termination setpoint. During normal
operation, this menu item will display
dashes, e.g. “33 -”.34 - Front Panel Ice Termination
Setpoint: Established the temperature
of the entering chilled water at which
ice making is terminated. This setpoint
is the active setpoint when the chiller is
in the AUTO/LOCAL, ice mode.
35 - Return Reset: Enables or disables
Return CWR, based on the current
Delta-T across the evaporator (e.g:
Entering Chilled Water Temp. - Leaving
Chilled Water Temp.).
36 - Zone Reset: Enables or disables
Zone  CWR, based on a zone
temperature sensor.
37 - Outdoor Reset: Enables or disables
Outdoor CWR, based on an outdoor
temperature sensor.
38 - Reset Ratio Setpoint: The reset
ratio, as a percent, to be used by the
UCM to calculate a reset chilled water
setpoint. See discussion in “Chilled
Water Reset”.
39 - Start Reset Setpoint: The start
reset temperature to be used by the
UCM to calculate a reset chilled water
setpoint. See discussion in “Chilled
Water Reset”.
3A - Maximum Reset Setpoint: The
maximum reset temperature to be
used by the UCM to calculate a reset
chilled water setpoint. See discussion
in “Chilled Water Reset”.
3b - External Circuit Lockout: When
enabled, individual circuit operation is
controlled by a remote, customer
specified/installed contact closure. See
External Circuit Lockout -Circuit #1 and
External Circuit Lockout -Circuit #2 in
the Installation - Electrical section. 
						

							102RTAA-IOM-3
Menu 4 – Factory Display #1
40 - Leaving Water Temp. Cutout
Setpoint: Establishes a leaving chilled
water temperature, below which the
UCM will begin unloading
compressors and, if necessary,
terminate unit operation. See
discussion in “Leaving Water
Temperature Cutout”. See Table 15 for
proper settings.41 - Low Refrigerant Temp. Cutout
Setpoint: Establishes a saturated
evaporator refrigerant temperature,
below which the UCM will begin
unloading compressors and, if
necessary, terminate unit operation.
See discussion in “Low Refrigerant
Temperature Cutout”. See Table 15 for
proper settings.
Table 15
Leaving Fluid Temperature Setpoints
Chilled Leaving Low
Water Water Temp Refrig Temp Recommended *** Solution Freeze
Setpoint - F Cut out - F Cut out - F % Ethylene Glycol Point - F
40 35 22 0 32
39 34 20 3
38 33 18 6
37 32 17 8
36 31 15 10 25
35 30 14 12
34 29 12 14
33 28 11 15 21
32 27 9 17
31 26 7 19
30 25 6 20 16
29 24 4 21
28 23 2 23
27 22 0 25 10
26 21 -1 26
25 20 -3 28
24 19 -5 29
23 18 -6 30 4
22 17 -8 31
21 16 -10 33
20 15 -11 34
19 14 -13 35 -3
18 13 -15 36
17 12 -17 37
16 11 -18 38
15 10 -19 39
14 9 -21 40 -11
13 8 -23 41
12 7 -24 42
11 6 -26 43
10 5 -27 43
9 4 -29 44
8 3 -31 45 -21
7 2 -32 46
6 1 -34 47
5 0 -35 47
4 - 1 -37 48
3 -2 -38 49
2 -3 -39 50 -32
1 -4 -39 50
0 -5 -39 50
***Recommended % Ethylene Glycol will give freeze protection consistent with other
chiller safety controls (solution freeze point is nominally 10 F above refrig temp cutout). 
						

							103RTAA-IOM-3
42 - Condenser Limit Setpoint:
Establishes a percentage of the
condenser high pressure cutout, above
which the UCM will begin unloading
compressors and, if necessary,
terminate unit operation.
43 - Lead Lag: Enables or disables the
Auto Lead/Lag feature. See discussion
in “Auto Lead/Lag”.
44 - SI Display Units: When set to
“Enable”, the display units are
converted from OF to IC and PSIG to
Kilopascals Gauge.
45 -Unit Line Voltage (Optional):
Establishes the line voltage coming
into the unit and calibrates the UCM for
Under/Over voltage protection and
display of % volts. See “Unit Power
Supply”.
46 - Under/Over Voltage Protection
(Optional): Enables or disables the
optional under/over voltage protection
feature, if installed.
47 - Phase Unbalance Protection:
Enables or disables the phase
unbalance protection feature. See
discussion in “Phase Unbalance
Protection”.
48 - Phase Reversal Protection:
Enables or disables the phase reversal
protection feature. See discussion in
“Reverse Rotation Protection”.
49 - Superheat Setpoint: Establishes
the temperature of the refrigerant
superheat in the evaporator.
4A - EXV Control Response Setpoint:
Establishes EXV control
responsiveness. If the control appears
to be too responsive, decrease the
setpoint. Increase the setpoint if the
control appears to be sluggish. The
UCM-based default is designed to
handle most applications and
adjustment is usually not necessary.
4b - LWT Control Response Setpoint:
Establishes LWT control
responsiveness. If the control appears
to be too responsive, decrease the
setpoint. Increase the setpoint if the
control appears to be sluggish. The
UCM-based default is designed to
handle most applications and
adjustment is usually not necessary.4C - ICS Address (Optional): Sets the
address at which a remote controller,
such as a Tracer, multiple-machine or a
remote display panel, can find the
chiller on a Bidirectional
Communications Interface. To use this
interface, the optional 1U2 module
must be installed. The Tracer will look
for the chiller at addresses 55, 56, 57,
58, 59 or 60. The UCM-based default is
address 55. When multiple chillers are
connected to the Bidirectional
Communications Interface, each chiller
must have a unique address, e.g. 55, 56
and 57 for three chillers.
For chillers with the Remote Display
Panel, set the address to “32”. See
RTAA-IOM-2 for further information on
Remote Display Panel.
4d - Fan Control Deadband Bias
Provides sensitivity adjustment of
condensing fan control logic. Must be
set at “0”. Settings other than “0” are
not permitted.
4E - Programmable Relays Setup:
Used for selection of the Alarm/
Running/ Maximum Capacity contact
outputs. See Alarm/Running/Maximum
Capacity Outputs in the Installation -
Electrical section.
4F - Restart Inhibit Timer: Used to
adjust the time (in seconds) between
the power-up of a unit (or the switching
from the STOP/RESET position) and
the initiation of the compressor start
sequence, provided there is a call for
cooling. The typical setting is 120
seconds, but a time as short as 30
seconds may be set.
Note: The anti-recycle timer, which
provides 5 minutes between start
cycles, is not affected by this menu
item. 
						

							104RTAA-IOM-3
Menu 5 – Factory Display #2
50 - Number of Compressors: Set to
the number of compressor installed in
the unit.
51 - Compressor Tons: Set to the rating
in tons, of the each installed
compressor. See Table 2.
52 - Low Water Temperature EXV Gain
Compensation: Set to “E” if the unit
will ever operate with a leaving chilled
water temperature of 40 F or less.
53 - Fan Control: Set to “E”.
54 - Fans Per Circuit: Establishes the
number of fans installed on each
circuit. See Figures 45 and 46.
55 - Reduced Inrush Starting: Set to
“d” if across-the-line wiring or to “E” if
Wye-Delta wiring.
56 - Compressor Current Overload
Setting: Establishes the compressor
motor current overload setting, which
must agree with the DIP Switch
settings on the corresponding
compressor modules. See Table 16.
Compressor Compressor Module
A ................................. 1U4
B .................................. 1U5
C .................................. 1U6
D ................................. 1U757 - GP Compressor Unit: This menu
item must be set to “d”. The unit is not
to be operated unless a “d” is
displayed in this item.
58 - Low Ambient, Half Airflow Fan
(Halfpitch Blades on Lead Fan(s): Set
this menu item per the following unit
selections
RTAA 130 - 200 Standard Ambient = d
RTAA 130 - 200 Low Ambient = E
RTAA 240 - 400 All = E
59 - LATSM: Set this menu item to “d”.
5A - NNS: Set this menu item to “d”.
5b - Number of EXV Valves per Circuit:
Set this menu item per the following
unit selections
RTAA 130 - 200 Circuit 1 = 1
Circuit 2 = 1
RTAA 240 - 300 Circuit 1 = 2
Circuit 2 = 1
RTAA 340 - 400 Circuit 1 = 2
Circuit 2 = 2
5C - Future Option: Set this menu item
to “d” for both Circuit #1 and Circuit #2.
Table 16
Compressor Overload DIP Switch Settings
Overload Setting
Compressor CT DIP Sw/Decimal**
Tons Volts.Hz RLA Ext* 12345
70 200/230.60 280 -05 00100/04
460.60 122 -02 10000/16
575.60 98 -01 11110/30
85 200/230.60 306 -05 01011/11
460.60 133 -02 10110122
575.60 107 -02 00110/06
100 200/230.60 375 -05 11010/26
460.60 163 -03 10000/16
575.60 131 -02 10110122
*The CT base part number is X13580253. The numbers in this column are suffixes to the
base number.
**On the DIP switch, 1= ON, O= OFF. The decimal number is the setting Menu Item 56. The
DIP switch setting and the decimal display of Item 56 comprise a redundant overload
setting. If the values are not set to match, the related compressor(s) will continue to run,
but a diagnostic will be initiated, both settings will be ignored, and the UCM will use the
lowest possible trip setting value. 
						

							105RTAA-IOM-3
Table 17
Compressor(s) Current Limit Setpoint vs Chiller Current Limit
Setpoint (CLS)
Number of Compressors on a UnitTwo (130-215) Three (240-300) Four (340-400)Number of Number of Number of
compressors compressors compressors
System in operation in operation in operation
CLS One Two One Two Three One Two Three Four120% 120 120 120 120 120 120 120 120 120
100% 120 100 120 120 100 120 120 120 100
80% 120 80 120 120 80 120 120 107 80
60% 120 60 120 90 60 120 120 80 60
40% 80 40 120 60 40 120 80 53 40
Operational Features
Entering Evaporator Water
Temperature
When one or more compressors are
running, the UCM continually monitors
and compares the entering and leaving
evaporator water temperatures. If the
temperature of the entering water
drops more than 2 F below the leaving
water temperature for more than 100
degree F seconds, the UCM uses this to
indicate a loss of water flow through
the evaporator, will shut down the
chiller and will display an MMR
diagnostic. See Figure 53.
Current Limit Setpoint
The current limit setpoint (CLS) for the
chiller (front panel or remote) is entered
through the UCM menu. The current
limit setpoint for each compressor is
shown in Table 17.
Based upon current levels received at
the UCM, the compressor slide valve is
modulated to prevent the actual chiller
current from exceeding the CLS.
When a compressor is turned off, the
CLS for the remaining running
compressors shall be reset upward
immediately. When a compressor is
added, the CLS for the running
compressors shall ramped downward
at a rate not less than 10% RLA per
minute to the new setpoint.
Low Ambient Lockout
The lockout provides a method for
preventing unit start-up when the
outdoor air temperature is below the
setpoint. If the outdoor temperature
goes below the setpoint during
operation, the UCM will go through a
normal shutdown of the unit. If the
outdoor temperature subsequently
increases to 5 F above the setpoint, the
UCM will automatically re-enable the
unit.
Electronic Expansion Valve (EXV)
Test
This test can be performed only when
the chiller switch is in the STOP/RESET
position. It will confirm proper
operation of the electronic expansion
valve and the EXV module.
Once the test has been initiated at the
UCM, the UCM will:
1. Overdrive the EXV closed (1250
steps)
2. Overdrive the EXV open (1250 steps)
3. Overdrive the EXV closed (1250
steps) 4. Reset the display to disable
and end the test
The EXV produces an audible clicking
sound only when it is driven against its
end stops. Step 1 drives the EXV to its
closed position, during which time
service personnel can move from the
UCM to the EXV.
Note: A tool may be needed to aid in
hearing the clicking of the EXV, such as
a screwdriver held between the EXV
and the ear.When Step 1 completes, the clicking
stops and the UCM begins to open the
EXV. When the EXV is fully opened, the
valve will begin to click against its end
stop. The service personnel must be
prepared to time the period between
the end of clicking in Step 1 and the
beginning of clicking in Step 2.
The time between the end of clicking in
Step 2 and the beginning of clicking in
Step 3 must also be recorded. The time
for the EXV to go from fully closed to
fully open should be approximately 15
seconds and the time to go back to
fully closed is approximately 15
seconds.
Current Overload Protection
The UCM continually monitors
compressor current to provide unit
protection in the event of an
overcurrent or locked rotor condition.
Protection is based on the phase with
the highest current and, if limits are
exceeded, the UCM will shutdown the
compressor and will display an CMR
diagnostic. See Figure 53.
Leaving Chilled Water Temperature
Control
If the chiller switch is in the AUTO
REMOTE position and a remote chilled
water setpoint has been
communicated, the UCM will control to
that setpoint. Otherwise, it will control
to the front panel setpoint. Control is
accomplished by both staging
compressors and modulating the slide
valves on each compressor.
Upon start-up, if the leaving water
temperature is dropping 1.5 F per
minute or faster, the chiller will not load
further. 
						

							106RTAA-IOM-3
Chilled Water Reset (CWR)
As an option, the UCM will reset the
chilled water temperature setpoint,
based on either the return water
temperature, zone air temperature, or
outdoor air temperature. The following
are selectable:
1. One of four RESET TYPEs, from top
to bottom in order of reset:
 no CWR
RETURN WATER
TEMPERATURE RESET ZONE
TEMPERATURE RESET
OUTDOOR AIR TEMPERATURE
RESET
 The UCM will not permit more than
one type of reset to be selected in
Menu 3.
2. RESET RATIO Setpoints. For
OUTDOOR AIR TEMPERATURE
RESET, there are both positive and
negative reset ratios.
3. START RESET Setpoints.
4. MAXIMUM RESET Setpoints. The
maximum resets are with respect to
the chilled water setpoint.
No matter which type of reset is
selected, all parameters are factory set
to a predetermined set of values. Field
adjustment of 2, 3, or 4, above, is
usually not required.
The equations for each type of reset
are:
RETURN WATER TEMPERATURE
RESET
CWS’= CWS + RESET RATIO
[START RESET - (TWE - TWL)]
and CWS’> or = CWS
and CWS’- CWS < or = MAXIMUM
RESET
ZONE TEMPERATURE RESET
CWS’= CWS + RESET RATIO
[START RESET - TZONE]
and CWS’> or = CWS
and CWS’- CWS < or = MAXIMUM
RESET
OUTDOOR AIR TEMPERATURE RESET
CWS’= CWS + RESET RATIO
[START RESET - TOD]
and CWS’> or = CWS
and CWS’- CWS < or = MAXIMUM
RESET
CWS’ is the new chilled water setpoint.CWS is the active chilled water setpoint
before any reset has occurred.
RESET RATIO is a user adjustable gain.
START RESET is a user adjustable
reference.
TZONE is the zone temperature.
TOD is the outdoor temperature.
TWE is the entering evaporator water
temperature.
TWL is the leaving evaporator water
temperature.
MAXIMUM RESET is a user adjustable
limit, providing the maximum amount
of reset.Note: When any type of CWR is
enabled, the UCM will step the CWS
toward the desired CWS’ (based on the
above equations and setup
parameters) at a rate of 1 F every 5
minutes. This applies when the chiller
is both running and off. Normally the
chiller will start at the Differential-to-
Start value above a fully reset CWS or
CWS’.
The values for RESET RATIO for each type of reset are:
Reset Increment Factory
Reset Ratio English Increment Default
Type Range Units Sl Units Value
Return 10 to 120% 1% 1% 50%
Zone 50 to 300% 1 % 1 % 100%
Outdoor 80 to -80% 1 % 1 % 10%
The values for START RESET for each type of reset are:
Start Increment Factory
Reset Reset English Increment Default
Type Range Units Sl Units Value
Return 4 to 30 F 1 F 0.1 C 10 F (5.6 C)
(2.2 to 16.7 C)
Zone 55 to 85 F 1 F 0.1 C 78 F (25.6 C)
(12.8 to 29.4 C)
Outdoor 50 to 130 F 1 F 0.1 C 90 F (32.2 C)
(10 to 54.4 C)
The values for MAXIMUM RESET for each type of reset are:
Maximum Increment Factory
Reset Reset English Increment Default
Type Range Units Sl Units Value
Return 0 to 20 F 1 F 0.1 C 5 F (2.8 C)
(-17.8 to -6.7 C)
Zone 0 to 20 F 1 F 0.1 C 5 F (2.8 C)
(- 17.8 to -6.7 C)
Outdoor 0 to 20 F 1 F 0.1 C 5 F (2.8 C)
(- 17.8 to -6.7 C) 
						

							107RTAA-IOM-3
Leaving Water Temperature Cutout
This temperature cutout provides
protection against freezing caused by
low leaving water temperature. The
setpoint is both factory set and
adjustable from Menu 4. Temperatures
below the setpoint will cause the UCM
to accelerate reduction of chiller
capacity, even to the point of
compressor shutdown. A non-latching
diagnostic will be generated if the LWT
is below the cutout for more than 30
degree F seconds.
There must be a minimum of 5 F
between the cutout temperature and
both the front panel and active chilled
water setpoints. The UCM will not
permit setting of either the front panel
or active chilled water temperatures
less than 5 F above this cutout
temperature and the display will flash
the last valid temperature.
If the leaving water temperature cutout
is set upward, the UCM will maintain
the 5 F minimum and will raise the
settings on the front panel and active
chilled water setpoints, if necessary.
Low Refrigerant Temperature
Cutout
Both circuits are protected from a
saturated evaporator refrigerant
temperature that goes below this
setting. The cutout setpoint must be a
minimum of 15 F lower than the front
panel or active chilled water setpoints.
There must be a minimum of 15 F
between the cutout temperature and
both the front panel and active chilled
water setpoints. The UCM will not
permit setting of either the front panel
or active chilled water temperatures
less than 15 F above this cutout
temperature and the display will flash
the last valid temperature.
If the leaving water temperature cutout
is set upward, the UCM will maintain
the 15 F minimum and will raise the
settings on the front panel and active
chilled water setpoints, if necessary.
If the saturated evaporator refrigerant
temperature for a circuit drops below
this setpoint for longer than 30 degree
F seconds, the circuit will be shutdown
and a CMR diagnostic will be
displayed.
Low Ambient Temperature Start
The Low Refrigerant Temperature
Cutout (LRTC) on a circuit is ignored,
briefly, each time the circuit is started.
The “ignore time” is a function of the
Saturated Condenser Refrigerant
Temperature at the time the
compressor starts, as shown in Figure
54.
Low Refrigerant Temperature
Cutout Retry
If the LTRC trips despite the low
ambient temperature start logic, the
circuit will be permitted to shutdown
and retry one time
If the LRTC trips within the first 20
minutes after initial start but after the
Low Ambient ignore time (grace
period), the compressor stops
immediately and the Restart Inhibit
timer is set to 1 minute. After time
expires, the compressor will restart if
there is a call for cooling.
If the LRTC trips again during the grace
period, a CMR diagnostic will occur. If
there is an LRTC trip anytime after the
grace period, a CMR diagnostic will
occur.
Figure 54
Low Refrigerant Temperature
Cutout Ignore Time
Low Refrigerant Temperature Cutout Time - vs - Saturated Condenser Refrigeration Temperature 
						

							108RTAA-IOM-3
Auto Lead/Lag
This feature is enabled/disabled in code
43, menu 4. When enabled, the UCM
will start the compressor with the
fewest starts and stop the compressor
with the greatest hours, as determined
by the “Compressor Starts”
accumulator (code 29, menu 2) and the
“Compressor Hours” (code 2A, menu
2). (Display is optional). This will tend to
balance out hours and starts equally
over all compressors. For efficiency
improvement, when there are 2
compressors operating, they will be on
opposite circuits. When disabled the
compressors will start per the following
chart.
RTAA RTAA RTAA
130-200 240-300 340-400
AAA
AB AC AC
ABC ABC ABCD
Phase Imbalance Protection
The UCM monitors the current in each
phase and calculates the percentage of
imbalance as follows:
% Imbalance = (I
x - l
ave) 
x 100
l
ave
l
ave = (11 + 12 + 13)
 / 3
l
x = phase with greatest difference from
l
ave (without regard to sign)
If code 47, menu 4, is enabled, and the
average three phase current is greater
than 80% RLA, and the percent of
imbalance is calculated to exceed 15%,
the UCM will shutdown the
compressor and display a CMR
diagnostic.
In addition to the 15% criteria, the UCM
has a non-defeatable 30% criteria
which has its own diagnostic. If the
15% criteria is enabled, it will always
display the 15% diagnostic first. The
30% criteria is always active when a
compressor is running, regardless of
% RLA.
Reverse Rotation Protection
The UCM monitors incoming current
during start-up and will shutdown the
compressor within one second, if
phase reversal is detected.
Caution: Phase relationships during
installation of unit power must be
carefully controlled to assure
compressor protection against
reversed phase rotation. See
Installation - Electrical.
DIP Switch Settings
Compressor Overload DIP
Switches
The settings for these switches are
shown in Table 16.
IPC Address
The [PC address set the address for
Inter-Processor Communications of the
UCM modules. The following is the IPC
DIP switch settings for the RTAA 130
400 modules.
IPC
DIP MODULE
SWITCH1U31U41U51U61U71U8
1 OFF OFF OFF ON ON OFF
2 OFF OFF ON OFF ON ON
2-10 VDC/4-20 made Input for
External Chilled Water Setpoint
(CWS) and Current Limit Setpoint
(CLS)
When either external CWS or external
CLS is used on the optional Module
1U2, DIP switch SW1 positions 1 and/or
2 must be set to accommodate the type
of signal source the customer has
chosen, either 2-10 VDC or 4-20 mA.
SW1 - 1 sets 2-10 VDC/4- 20 mA for
external CWS. SW1 -2 sets 2-10 VDC/4-
20 mA for external CLS. The “OFF’
setting configures the external input for
2-10 VDC; the “ON” setting configures
the external input for 4-20 mA. 
						

							109RTAA-IOM-3
2. The display will flash the Current
Operating Code “A”, followed by a
fully blank display for all other
diagnostics (CMR, CAR, and IFW
diagnostics). This is to call attention
to the detection of some type of
failure.
Depressing the Display Down key will
advance the display to the “Last (most
recent) Diagnostic Code”. The display
will “flash” if any diagnostic exists that
requires a manual reset to restore full
unit operation. The display will be
continuous if no manual reset is
required to restore full operation. The
“Last Diagnostic Code” will be retained
until the unit control is reset or a new
diagnostic occurs.
Depressing the Display Down key will
then cause the display to show any
“Other Diagnostic Codes” that have
occurred since the “Other Diagnostic
Codes” was last reset. Any specific
diagnostic will not be shown more than
once, even if it has occurred more than
once. No time sequence of occurrence
is provided. The display will “flash” if
the current logical status of the
condition that caused the diagnostic
still exists or if it is an MMR or MAR
diagnostic. Flashing means the
condition still exists if it is a MAR, CAR,
or IFW diagnostic or that a manual
reset is required if it is a MMR or CMR
diagnostic.
By depressing the Display Down key
after the last of the “Other Diagnostic
Codes”, the display can be advanced to
setpoint adjustment, unit temperature,
and other data displays.
Depressing the Display Down key
following the last data display in the
menu (either operating, service,
auxiliary options, or factory) will return
the display to the top of the display
menu, “P Menu Number”. If the menu
selected is Menu 0 and either an MMR
and MAR diagnostic is still active, when
selected again, the operating code will
“alternate” with the highest priority
MMR or MAR, as in item 1. above.
Otherwise, in all other cases, the
current operating code will be
displayed continuously.If any diagnostics have been detected
since the last unit reset, the “Last
Diagnostic Code” will be cleared when
the chiller switch is moved from the
STOP/ RESET position to either of the
AUTO positions. The display will show
“A 88” for 0.5 to 5 sec. following the
reset, before returning to the display of
the operating code.
The above step will not clear the
“Other Diagnostic Codes” menu item.
To clear this, depress and hold the
Display Down key while moving the
chiller switch from the STOP/RESET
position to either of the AUTO
positions.
Mechanical Control Settings
The settings for the High Pressure
switch, Oil Pressure switch, and
Winding Thermostat are shown below:
CLOSEOPEN
Compressor 300 ±20 405 ±7
Discharge
High Pressure
Switch - PSIG
Compressor Oil 47 50 ±3
Pressure Switch
-PSID
Compressor 181 221
Motor Winding
Thermostat - F
Domestic Water 115 130
Heater Solenoid
Thermostat - F
Diagnostics and
Troubleshooting
If no diagnostics exist, the selected
menu item will be displayed
continuously. When a diagnostic
occurs, the display will switch to the
Menu “0” and, depending on the
nature of the diagnostic, will do one of
the following:
1. The display will “alternate” between
the Operating Code “A” at the time
of failure and the Diagnostic Code
“C” for any condition that causes the
entire shutdown (MMR and MAR
diagnostics). The display will
alternate between “A XX” and “C
YY”, where YY is the MMR or MAR
diagnostic that caused the machine
to shutdown. If multiple MMR or
MAR diagnostics occur, YY will be
the active diagnostic with the
greatest priority. Priority, from the
highest to lowest, shall be as follows:
CdContactor - Cprsr D (MMR)
CCContactor - Cprsr C (MMR)
CbContactor - Cprsr B (MMR)
CAContactor - Cprsr A (MMR)
413CPM module indicates EXV
module communications loss (MMR)
431EXV Module indicates CPM
module communications loss (MMR)
FdEmergency Stop (MMR)
AbEvaporator Leaving Water
Temperature Sensor (MMR)
8EEvaporator Entering Water
Temperature Sensor (MMR)
8AChilled Water Flow (Entering
Water Temperature) (MMR)
d8Under Voltage (MAR)
d7Over Voltage (MAR)
EdChilled Water Flow Interlock
(MAR)
C6Low Chilled Water Temp.
(Unit On) (MAR)
When multiple diagnostics exist and a
diagnostic with a higher priority is no
longer active, the diagnostic with lower
priority will replace it in the alternating
“A XX” and “C YY” displays.
Note: MMR diagnostics only become
inactive after a RESET MAR diagnostics
become inactive when the condition
that caused them clears. 
						

							110RTAA-IOM-3
Table 18
Diagnostics and Troubleshooting Chart
In the table below, a “LATCHING” diagnostic is a condition which shall cause the machine or a portion of the machine as
noted to shut down and shall require a manual reset to restore operation. A diagnostic that is non-latching shall reset
automatically when the condition causing the diagnostic goes away. A non-latching diagnostic shall shut down the machine
or a part of the machine if so indicated. If a diagnostic is informative only, no machine or circuit action is taken except to load a
diagnostic code into the last diagnostic register.
Diagnostic Types (And Action)
MMR = Machine Shutdown, Manual Reset
MAR = Machine Shutdown, Auto Reset
CMR = Circuit Shutdown, Manual Reset
CAR = Circuit Shutdown, Auto Reset
IFW = Information/Warning
DIAG.
ACTIVE
CODE DIAGNOSTIC DESCRIPTION TYPE MODES CAUSE
87 External Chilled Water IFW All a. Not “Enabled”: No Diagnostics Setpoint
b. “Enabled”: Out-of-Range Low, set diagnostic.
 Out-of-Range Hi, no diagnostic.
89 External Current Limit IFW All a. Not “Enabled”: No Diagnostics Setpoint
b. “Enabled”: Out-of-Range Low, set diagnostic.
 Out-of-Range Hi, no diagnostic.
8A Chilled Water Flow MMR Any Circuit a. The entering evaporator water fell (Ent. Wtr. Temp.)
Energized  below the leaving evap. water temp. by more than
 2 F for 100 F-seconds.
b. Causes to trip this diagnostic loss of chilled water
 flow or a calibration shift in the evap. water temp.
 sensors.
8E Evap. Entering Water Temp. Sensor MMR All Open or Short
8F Cond. Rfgt. Temp. Sensor - Ckt 1 CMR All Open or Short
90 Cord. Rfgt. Temp. Sensor - Ckt 2 CMR All Open or Short
93 Evap. Rfgt. Temp. Sensor - Ckt 1 CMR All Open or Short
94 Evap. Rfgt. Temp. Sensor - Ckt 2 CMR All Open or Short
9A Cord. Entering Wtr. Temp. Sensor IFW All Shorted condenser temperature sensor
(no diagnostic on open circuit).
9b Cond. Leaving Wtr. Temp. IFW All Shorted condenser temperature sensor
Sensor (no diagnostic on open circuit).
AO Zone Temperature Sensor IFW All Open or Short
a. Use end of range value (whatever value the open or
short gives).
(Zone Reset Selected) b. Clear diag. when the resistance returns to normal
range.
c. If Shorted, go into the ice making mode if
“Ice Machine Control” is enabled.
Zone Temperature Sensor None All a. If Open, do normal chiller control .
(Zone Reset Not Selected) b. If Shorted, go into the ice making mode if “Ice
Machine Control” is enabled.
A1 Outdoor Air Temp. Sensor IFW All Open or Short
(Either Outdoor Air Reset a. Use end of range value (whatever
or Low Ambient Lockout value the open or short).
Selected) b. Clear diag. when the resistance returns to
normal range.