Trane RTHC - Page 103

Diagnostic Table
RTHC-SVD01B-EN 97
Low Discharge
Superheat
MMR
friendly
Stepper
1U3
Any Running
Modes
a.While Running Normally, the Discharge
Superheat was less than 12 degrees F +-
1F for more than 6500 degree F seconds.
The must hold value is 13F while the must
integrate value is 11F.
b. At startup the UCP2 ignores the
Discharge Superheat for a minimum of 5
minutes and a maximum of 5.5 minutes.
This timer should be reset everytime the
chiller starts up. Discharge superheat shall
be monitored only while the chiller is in any
of the run modes.
Confirm oil and
refrigerant charges.
Confirm EXV operation
and liquid level sensor.
Low Evap Rfgt
Temp .
MMR
immediate
Stepper
1U3
Starter
Contactor
Energized
a. The Saturated Evap Rfgt Temp dropped
below the Low Rfgt Temp. Cutout Setpoint
when the circuit was running for 60 degree
F seconds. Special note: During timeout of
trip integral, the unload solenoid shall be
energized continuously, and load solenoid
de-energized continuously- Normal load
unload operation will be resurmed in trip
integral is reset by return to temps above
cutout setpoint.
Confirm operation of
sensor, EXV and
Stepper module.
Confirm refrigerant
charge.
Low
Evaporator
Liquid Level
MMR
friendly
Stepper
1U3
Starter
contactor
energized (all
stop modes)
The liquid level sensor is seen to be at or
near its low end of range for 80 contiguous
minutes while the compressor is running
Check EXV, Sensor,
Stpr Module & Rfgt
Charge
Low Oil Flow MMR
friendly
Chiller
1U1
Cprsr
Energized
The oil flow pressure switch detects no flow
(high logic state) for 5 contiguous seconds.
Check Oil System
(Master Oil Line
Solenoid Valve & Oil
Filter, Hand valves, and
Differential Pressure
switch)
Table 14-2: Diagnostic Table
Diagnostic
Description
Type/
Shutdown
Action
Module
Calling
Out Diag.
Operating
Modes
Diagnostic is
Active
Cause Help Message