Carrier VECTOR 1800 MT - Page 233

7-102
62-11039
Alarm
NO.
Steps ALARM / CAUSE CORRECTIVE ACTION
P191 CHECK UL2
• TRIGGER–ON: The pressure differential between suction and discharge pressures did not change as
expected when the UL2 (Front/Rear) Unloader was de-energized/loaded (discharge pressure should rise
and suction pressure should drop) or when it was energized/unloaded (discharge pressure should drop
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• UNIT CONTROL: Engine and standby operation: Pretrip will fail and display “PRETRIP FAIL AND
COMPLETED”.
• RESET CONDITION: Auto Reset if pre--trip mode is started again, or alarm may be manually reset via
keypad or by turning the unit off, then back on again.
NOTE: Follow the steps below until a problem is found. Once a repair or correction has been made, clear the
alarm(s). (See Note 1) Operate the unit through the appropriate modes to see if any active alarm occurs. Continue
with the steps below as necessary.
1. Check wiring to DPT & SPT
a. Verify that correct wires are
connected to each transducer
Plugs to transducers are the same. The correct wire plug
must be connected to the proper transducer.
2. Check for Check UL2 Alarm
a. Check for alarm 86 or P164 Alarm conditions must be corrected and the alarm cleared
to continue
3. Confirm Compressor Suction Pressure Transducer Is Working
a. Check CSP Attach manifold gauge set and compare CSP reading from
microprocessor display.
Repair and Replace if required.