10 - 6 RTHC-IOM-1C
External Current
Limit Setpoint
IFW-AR N/A a. Not “Enabled”: no diagnostics.
b. “Enabled “: Out-Of-Range Low or Hi, set diagnostic, default CLS
to next level of priority (e.g. Front Panel SetPoint. This IFW
diagnostic will automatically reset if the input returns to the normal
range.
Check Signal At
Input
EXV Electrical
Drive Circuit
MMR N/A The Stepper module has detected a wiring or motor fault on the EXV
output circuit just prior to EXV pre-position. The EXV motor is not
driven if a problem is detected. Miswires or faults that occur in the off
cycle can be detected and damage to module prevented at start-up.
Check Stepper
Module, Wiring, &
Motor.
High Cprsr
Discharge Temp.
MMR Immediate a. The discharge temp. exceeded 190
°
F + or - 5
°
F.
b. Time to trip from trip value exceeded shall be 0.5 to 2.0 seconds.
(Note: The trip may be an “instantaneous trip” but consistent with the
analog input filtering function.)
c. Immediate shutdown is preferred over friendly because unloading
the compressor will generally increase the discharge temperature.
See
Troubleshooting
Service Bulletin
High Diff. Rfgt
Pressure
MMR Friendly a. The difference between the Condenser pressure and the
evaporator pressure exceeded 160 PSID for 0.8-5.0 seconds. 152
PSID must hold, 152+ to trip in one hour.
See
Troubleshooting
Service Bulletin
High Evaporator
Liquid Level
MMR Friendly The liquid level sensor is seen to be at or near its high end of range
for 80 continuous minutes while the compressor is running
Check EXV,
Sensor, Stpr
Module & Rfgt
Charge
High Pressure
Cutout Tripped
MMR Immediate A high pressure cutout was detected. C.O. on rise @ 180 psig, reset
at 135 psig (+/-5 psid on switching tolerance) Note: Pressure relief
valve is 200 Psi +/- 2%,
Check Condenser
Water Temp.
High Restart
Inhibit Timer
Warning
IFW N/A The restart inhibit timer has reached a maximum threshold of 15
minutes. This indicates excessive chiller cycling, steps should be
taken to correct this.
Check for
Excessive Chiller
Cycling
Incorrect Chiller
Software Installed
MMR N/A The incorrect EPROM was loaded into this module. This diagnostic
is detected when a factory test computer sets the unit type to
something other than what the EPROM software was intended.
No Message
Required
Incorrect Stepper
Software Installed
MMR N/A The incorrect EPROM was loaded into this module. This diagnostic
is detected when a factory test computer sets the unit type to
something other than what the EPROM software was intended.
No Message
Required
Loss of Oil at
Compressor
(Running)
MMR Immediate In Running modes, Oil sensor detects lack of oil in line i.e. sensor
terminal voltage above 11.5 volts (clamped at 14.0 volts) for 23 volt-
seconds (778 bit for 1600 bit count-seconds). Upon transition from
wet to totally dry, a trip will occur in 15 seconds nominally
(distinguishing a liquid flow from a vapor flow).
Check Oil System
(Master Oil Line
Solenoid Valve &
Oil Return System
& Oil Detector
Sensor)
Loss of Oil at
Compressor
(Stopped)
MMR Oil Sensor detects a lack of oil trapped in line feeding compressor
for 2 continuous minutes after the oil line solenoid is opened for pre-
start mode. Note: Compressor start is delayed (up to an additional
90 sec) from the normal 30 sec of pre-start, waiting for oil to be
detected
Check Oil System
(Master Oil Line
Solenoid Valve &
Oil Return System
& Oil Detector
Sensor)
Low Chilled
Water Temp: Unit
Off
IFW-AR N/A a. The chilled water temp. fell below the cutout setpoint while the
compressor was not running for 30
°
F Seconds. Automatic Reset of
the IFW diag shall occur 2
°
F (1.1
°
C) above the cutout setpoint.
Check Flow,
Sensor, Wiring and
Rapid Load Loss
Low Chilled
Water Temp: Unit
On
MAR Friendly a. The chilled water temp. fell below the cutout setpoint while the
compressor was running for 30
°
F Seconds. Automatic Reset of the
MAR diag shall occur 2
°
F (1.1
°
C) above the cutout setpoint.
Check Flow,
Sensor, Wiring and
Rapid Load Loss
Diagnostic
Description
Diagnostic
Type
Shutdown
Action
Cause Help Message
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