Carrier 69NT40-541-300, Операция и обслуживание, Страница: 72 / 152

T-318 3 − 40
Table 3-7 Controller Pre-Trip Test Codes (Sheet 5 of 6)
P8-1
Perishable Mode
Pull Down Test /
eAutofresh CO
2
Sensor Calibration
Control temperature must be at least 15.6 ° C (60 ° F).
The set point is changed to 0 ° C (32 ° F), and a 180 − minute timer is started. The
left display will read “P8-1,” the right display will show the supply air temperature.
The unit will then start to pull down the temperature to the 0
°
C set point.
The test passes if the container temperature reaches set point before the
180 − minute timer expires.
On units where the CO
2
Sensor Status indicates that a CO
2
sensor is present,
calibration of the CO
2
sensor will be attempted during P8 − 1. Once P8 − 1 begins,
calibration will be attempted when the supply temperature goes below 5 ° C. If
the CO
2
sensor voltage reads within the 0.95 <>1.15Vdc range before the end of
P8 − 1, the sensor will be calibrated by holding the CO
2
zero line low for 4
seconds. Once calibration is performed, the sensor voltage will be verified to
make sure it is in the 0.95 to 1.05 Vdc range. If the voltage is not within this
range, CO
2
sensor calibration fails.
P8-2
Perishable Mode
Maintain
Temperature Test
Test P8-1 must pass for P8-2 to execute.
A fifteen minute timer is started, and the system will attempt to minimize control
temperature error (supply temperature minus setpoint) until the timer expires.
The control temperature will be sampled each minute starting at the beginning of
P8-2.
During P8-2, the left display will read “P8-2,” and the right display will show the
supply air temperature.
When the test is completed, the average control temperature error will be
compared to the pass/fail criteria.
Test passes if the average temperature error is /
− 1.0 ° C.
Test fails if the average temperature error is greater than +/ − 1.0 ° C, or if the
DataCorder supply temperature probe is invalid. If the test fails, the control
probe temperature will be recorded as − 50.0
°
C.
P9 Test - DTT Close and Open Test: The DTT in this control is not a physical device, with actual metallic con-
tacts, it is a software function that acts similar to a thermostat. Using various temperature inputs, the DTT func-
tion determines whether a thermostat mounted on the Evaporator Coil would have OPEN or CLOSED contacts.
Primarily, the DTT function operates based on the temperature reading from the Defrost Termination Sensor.
P9-0
DTT Closed and
Open Test
During P9-0 the defrost temperature sensor (DTS) reading will be displayed on
the left display. The right display will show the supply air temperature.
The unit will run FULL COOL for 30 minutes maximum until the DTT is consid-
ered closed. Once the DTT is considered closed, the unit simulates defrost by
running the heaters for up to two hours, or until the DTT is considered open.
Test fails if:
The DTT is not considered closed after the 30 minutes of full cooling
HTT opens when DTT is considered closed or if return air temperature rises
above 248 ° C (120 ° F).
Test passes if the DTT is considered open within the 2 hour heat cycle time limit.