Trane S*HF*20-75 Troubleshooting Manual page 129

Table 11: Diagnostics Troubleshooting Chart (continued)
Low Pressure Control
Open (Ckt-1 or Ckt-2)
Used With: DX cooling.
Module: MCM
Low Refrigerant Charge
(Ckt-1 or Ckt-2)
Used With: DX cooling.
Module: MCM
Manual Reset Return
Pressure Limit Trip
Used With: Return Fan.
Module: MPM
Manual Reset Supply Air
Static Pressure Limit
Used With: VVDA units, or
CVDA/CVZT units with
supply air pressure sensor
installed.
Module: RTM
RT-SVP07B-EN
Problem: The LPC Switch
Input on the given circuit is
detected open for at least 6
seconds.
Check: State of refrigerant
charge for the given circuit.
Problem: The cooling
circuit of interest has been
active for 10 minutes and
the difference in the
entering and leaving
evaporator temperatures
has been greater than the
Evaporator Temperature
Differential Setpoint for 10
continuous minutes.
Check: Refrigerant charge,
temperature sensor values.
Problem: The return
plenum pressure has
exceeded the Return
Plenum Pressure High Limit
(3.5 IWC).
Check: Check return
plenum pressure, exhaust/
return damper actuators,
return pressure transducer
assembly and wiring, etc.
Problem: The supply air
pressure has exceeded the
Supply Air Pressure High
Limit Setpoint the 3rd
consecutive time while the
unit is operating in any
mode.
Check: Supply air
ductwork, supply fan speed
control, supply air pressure
transducer assembly and
wiring.
A "Lockout Circuit" request
is issued to the given
circuit's compressor
staging control function.
A "Lockout" request is
issued to the given circuit's
compressor Staging
Control Function.
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 "Supply Air Pressure
Shutdown" signal is sent to
the following functions:
a. Compressor Staging
Control,
b. Economizer Actuator
Control,
c. Heat Operation,
d. Supply Fan/Return Fan
Control,
e. IGV / VFD Control,
f. Exhaust Fan Control
g. Exhaust Actuator Control
DIAGNOSTICS Menu
(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.
(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."
(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.
(PMR) A manual reset is
required and can be
accomplished at the
Human Interface or by
Tracer, or by cycling the
power to the RTM.
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