General Information; Service Philosophy - Trane R Series Diagnostic Troubleshooting Repair

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General Information

The Unit Control Modules (UCMs) described in this troubleshooting guide
provide a microprocessor based refrigeration control system, intended for
use with Trane 70-125 ton helical rotor chillers. Six types of modules are
used, and throughout this publication will be referred to by their abbreviations
or their Line Wiring Drawing Designations, see
Table 1 Unit Control Module Designations
Line Drawing Controller Name
Designation Chiller Module
1U2 Options Module
1U3 Expansion Valve Module
1U4 & 1U5 Compressor Module
1U6 Clear Language Display
1U7 Interprocessor
Communications Bridge
(Remote Display Buffer)

Service Philosophy

With the exception of the fuses, no other parts on or within the modules are
serviceable. The intent of the troubleshooting is to determine which module
is potentially at fault and then to confirm a module problem. This is done
either through voltage or resistance measurements at the suspected input or
output terminals or by checking related wiring and external control devices
(connectors, sensors, transformers, contactors etc.) in a process of elimi-
nation. Once a problem has been traced to a module, the module can be
easily replaced using only basic tools. In general, all dip switch settings of the
replaced modules should be copied onto the replacement module's dip
switches before applying control power. CPM replacement is more involved
as there are numerous configuration and set-up items that must be
programmed at the Clear Language Display in order to insure proper unit
operation.
It is helpful to include with the return of a module, a brief explanation of the
problem, sales office, job name, and a contact person for possible follow-up.
The note can be slipped into the module enclosure. Early and timely
processing of Field Returns allows for real measurements of our product
quality and reliability, providing valuable information for product improvement
and possible design changes.
Table 1.
Abbrev.
CPM
CSR
EXV
MCSP A & B
CLD
IPCB
RLC-SVD03A-EN