96
SCXF-SVX01T-EN
Category Diagnostic
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.
Controls
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.
Reaction
A “supply air pressure shutdown” signal is sent to the following functions;
• Compressor staging control,
• Economizer actuator control,
• Heat operation,
• Supply fan control,
• VFD control,
• Exhaust fan control
• 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.
Reaction
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.
Reset
Required
(PAR) An automatic reset occurs after communication has been restored.
Mode Input Failure
Problem
The RTM mode input is out of range.
Check
Sensor resistance should be between 1 ohm and 40 ohms. If so, check field/unit wiring between sensor and RTM.
Reason for
Diagnostic
The mode input signal on the RTM is out of range (resistance < 1 ohm or resistance > 40 ohms).
Controls
Reaction
The system mode reverts to the default (HI set) system mode.
Reset
Required
(INFO) An automatic reset occurs after the mode input returns to its allowable range for 10 seconds.
N
NSB Panel Zone Temperature Sensor Failure
Problem
The NSB panel's zone temp sensor input is out of range. (This input is at the NSB panel, not on the unit itself).
Diagnostics
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