Trane S*HF*20-75 Troubleshooting Manual page 130

DIAGNOSTICS Menu
Table 11: Diagnostics Troubleshooting Chart (continued)
Manual Reset Space
Press Low Limit Trip
Used With: Return Fan w/
Statitrac.
Module: RTM
MCM Communications
Failure
Module: MCM
MDM Communications
Failure
Module: MDM
MPM Communications
Failure
Module: MPM
130
Problem: The building's
space pressure has
dropped below the Building
Pressure Low Limit
rd
Setpoint for the 3 time
without the building
pressure ever rising above
Building Pressure Setpoint
bottom deadband.
Check: Check return
plenum pressure, exhaust/
return damper actuators,
etc.
Problem: The RTM has lost
communications with the
MCM module.
Check: Check unit wiring
between RTM and MCM
module.
Problem: The RTM has lost
communications with the
MDM module.
Check: Check unit wiring
between RTM and MDM
module.
Problem: The RTM has lost
communications with the
MPM module.
Check: Check unit wiring
between RTM and MPM
module.
The unit will trip all outputs,
de-energize dx cooling,
staged heating, fans, etc.,
and will drive all analog
ouputs closed/stop, fan
speed, dampers,
modulating heat, etc.
A "Lockout" request is sent
to the Compressor Staging
Control function. And a fail-
safe function in the MCM
will cause all MCM outputs
to be zeroed and de-
energized.
All active commands and
setpoints provided by the
MDM module will be
canceled and/or ignored.
All binary outputs will be
de-energized and analog
output set to fail-safe.
Dehumidification control
function is disabled and a
compressor lockout
request is issued for the
Reheat Circuit (IPak:Ckt-2,
IPakII:Ckt-1)
a. All active commands
provided by the MPM
module will be canceled
and/or ignored. Return fan
control function is disabled
and a "Unit Shutdown"
request is issued.
b. For evaporative
condensing units, a lockout
request is issued, for all
circuits, to the compressors
staging control function.
(PMR) A manual reset is
required anytime after the
Diagnostic is set. The
Diagnostic can be reset by
the Human Interface or
Tracer, or by cycling power
to the RTM.
Note: See Auto Reset
Space Press Low Limit
Trip Above.
(PAR) An automatic reset
occurs after
communication has been
restored.
(PAR) An automatic reset
occurs after one complete
set of the required IPC
packets has been received.
(PAR) An automatic reset
occurs after one complete
set of the required IPC
packets has been received.
RT-SVP07B-EN