Unit installation

Diagnostics
96 SCXF-SVX01K-EN
UCM Reaction:The functions that designated the heat
module auxiliary temperature input as their input are
disabled.
Reset Required: (PAR) An automatic reset occurs after the
heat module auxiliary temperature input returns to its
allowable range for 10 seconds.
Heat Module Comm Failure
Problem:The RTM has lost communication with the heat
module.
Check: Check field/unit wiring between RTM and heat
module.
Reason for Diagnostic:The RTM has lost communication
with the heat module.
UCM Reaction: An “all heat off” request is sent to the heat
operation function.
If the unit has staged gas or electric heat, all heat module
outputs will be zeroed and deenergized.
If the unit has hydronic heat or chilled water installed, the
unit will turn off the supply fan and close the outside air
damper upon the occurrence of a heat module comm
failure. A failsafe function in the heat module will cause all
water valves to be set to 100% to provide full water flow.
Unless used for switching purposes (air handlers with
chilled water and mod gas, or chilled water and hydronic
heat) all binary outputs will be deenergized.
Reset Required: (PAR) An automatic reset occurs after
communication has been restored.
L
Low Air Temp Limit Trip
Problem:The low air temp limit has tripped. (Units with
steam or hot water heating, or air handlers with chilled
water cooling)
Reason for Diagnostic: A low air temp limit trip is detected
continuously for more than one second.This can occur if
the hydronic heat low air temp limit input closes for > 1
second, or if the chilled water low air temp limit trip input
opens for > 1 second. On units with both hydronic heat and
chilled water, both low air temp limit inputs are active, and
the unit will respond in the same manner regardless of
which input is used.
UCM Reaction:The UCM will initiate the following actions;
a. An “open all water valves”request is issued to the heat
module function, causing any steam, hot water, or chilled
water valves on the unit to open.
b. An “all heat off” request is issued to the heat control
function.
c. A “fan off” request is sent to the supply fan control
function.
d. A “close damper” request is sent to the economizer
actuator control function.
Reset Required: (PMR) A manual reset is required after the
low air temp limit trip condition clears.The diagnostic can
be reset at the unit mounted human interface, byTracer
Summit, or by cycling power to the RTM.
Low Pressure Control Open - Circuit 1, 2, 3, or 4
Problem:The Low Pressure Control (LPC) for Ckt #1, 2, 3,
or 4 is open.
Check: State of refrigerant charge for ckt #1, 2, 3, or 4.
Reason for Diagnostic:The Ckt # 1 LPC input is detected
open as described in the compressor protection function.
UCM Reaction: A “Lockout Ckt # 1, 2, 3, or 4” request is
issued to the compressor staging control function.
Reset Required: (PMR) A manual reset is required anytime
after the diagnostic is set.The diagnostic can be reset by
the human interface,Tracer Summit, or by cycling power
to the RTM.
M
Manual Reset SA Static Press Limit
Problem:The supply air static pressure went too high for
the third consecutive time.
Reason for Diagnostic:The auto reset supply air static
pressure limit diagnostic has occurred for the third time
while the unit is operating in occupied mode.
UCM Reaction: 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 control,
e. VFD control,
f. Exhaust fan control
g. Exhaust actuator control
Reset Required: (PMR) A manual reset is required and can
be accomplished at the HI,Tracer Summit, or by cycling
power to the RTM.
MCM Communications Failure
Problem:The RTM has lost communication with the MCM.
Check: Check field/unit wiring between RTM and MCM.
Reason for Diagnostic:The RTM has lost communications
with the MCM.
UCM Reaction: A “Lockout” request is sent to the
compressor staging control function. And a failsafe
function in the MCM will cause all MCM outputs to be
zeroed and deenergized.
Reset Required: (PAR) An automatic reset occurs after
communication has been restored.
Mode Input Failure
Problem:The RTM mode input is out of range.