Carrier NDK33BN0KB, Operation & Service Manual

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62-61753-21 7-21
Alarm
NO.
Steps ALARM / CAUSE CORRECTIVE ACTION
28 CHECK REFRIGERATION SYSTEM

TRIGGER ON: The refrigeration system is running and the discharge pressure is less than 0.34 bar
(5 psig) higher than suction pressure for more than 30 seconds.

UNIT CONTROL: Engine operation: alarm only or (if configured for shutdown) engine and unit
shutdown and alarm.
Standby operation: alarm only or (if configured for shutdown) refrigeration
system shutdown and alarm with PSCON still energized.

RESET CONDITION: Auto reset when discharge pressure is more than 1.36 bar (20 psig) above the
suction pressure when in alarm only, or auto reset after 30 minutes when shutdown is configured 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, the active
alarm should clear itself (refer to reset condition above). Operate the unit through the appropriate modes to see if
any active alarm occurs. Continue with the steps below as necessary.
1 Verify Compressor Is Running.
a. Check compressor Amp draw -
CCON T1-T2, T1-T3, T2-T3.
Check all three voltage legs. Readings must be in the
range as shown in Section 2.11.
2 Check System Pressures
a. Install Manifold Test Set and check
and compare compressor dis-
charge & suction pressures with
those shown on the microproces-
sor display.
Suction pressure must be above 3 psig (0.2 bar)
Discharge pressure must be more than 5 psig (0.3 bar)
higher than the suction pressure.
Suction & Discharge Pressures must have the same
reading on gauges & on microprocessor display.
NOTE: Microprocessor suction (CSP) and evapora-
tor (EVOP) pressure readings have a maximum
value of 100 psig (7.5 bar) The actual suction pres-
sure must be lower than 100 psig in order to per-
form this test.
3 Perform Pretrip Check
a. Clear Active Alarm list, then run
Pretrip & check for any new
alarms.
Any active alarms must be corrected and cleared be-
fore proceeding.
4 Check Compressor
a. Check compressor for excessive
vibration or noise
Replace compressor