Carrier 69NT40-541-505 Operation And Service Manual page 74

P7 Tests - High Pressure Tests: Unit is run at full capacity without condenser fan running to make sure that the
HPS opens and closes properly.
High Pressure Switch
P7-0
Closed
High Pressure Switch
P7-1
Open
P8 Tests Perishable Mode Tests: Pretrip tests P70 and P71 must have passed or have been skipped for these
tests to execute.
Perishable Mode
P8-0
Heat Test
T-368
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Table 4–7 Controller Pre-Trip Test Codes
With the unit running, the condenser fan is de-energized, and a 15 minute timer is
started. The right display shows discharge pressure if the unit is equipped with a
discharge pressure transducer (DPT). If no DPT is installed, the condenser pres-
sure transducer (CPT) reading will be displayed.
Test is skipped if:
Sensed ambient temperature is less than 7C (45F)
Return air temperature is less than 17.8C (0F)
The water pressure switch (WP) is open, indicating that the unit is operat-
ing with a water-cooled condenser
Test is skipped if the unit does NOT have:
A compressor discharge sensor (CPDS)
A discharge pressure transducer (DPT)
A condenser pressure transducer (CPT)
Test passes if the HPS opens within 15 minutes.
Test immediately fails if the following inputs are sensed to be invalid:
Compressor discharge sensor (CPDS)
Discharge pressure transducer (DPT)
Condenser pressure transducer (CPT)
Return temperature sensor (RTS)
Ambient sensor (AMBS)
Test will also fail if:
HPS fails to open within 15 minutes
Discharge temperature exceeds 138C (280F)
Discharge temperature is less than or equal to ambient temperature plus
5C (9F)
CPT or DPT pressure exceeds 27.42kg/cm
Test P70 must pass for P71 to execute.
The condenser fan is started and a 60 second timer is started.
Test passes if the high pressure switch (HPS) closes within the 60-second time
limit, otherwise, it fails.
If the container temperature is below 15.6C (60F), the set point is changed to
15.6C, and a 60-minute timer is started. The left display will read P80. The control
will then heat the container until 15.6C is reached.
If the container temperature is above 15.6C at the start of the test, then the test
proceeds immediately to test P81 and the left display will change to P81.
The test fails if the 180-minute timer expires before the control temperature reach-
es set point. The display will read P80, FAIL.
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2
4–44
(390psig)