Carrier Transicold 69NT40-561-001 Operation And Service Manual page 87

P8-1 Perishable Mode Pull
Down Test / eAutofresh
CO Sensor Calibration
2
P8-2 Perishable Mode Maintain
Temperature Test
P9 Test - DTT Close and Open Test: The DTT in this control is not a physical device, with actual metal-
lic contacts, it is a software function that acts similar to a thermostat. Using various temperature inputs,
the DTT function 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
Table 4–7 Controller Pre-trip Test Codes
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
ent, calibration of the CO
1 begins, calibration will be attempted when the supply temperature goes
below 5°C. If the CO
range before the end of P8-1, the sensor will be calibrated by holding the
CO zero line low for 4 seconds. Once calibration is performed, the sensor
2
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
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 tim-
er 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 within +/- 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 con-
trol probe temperature will be recorded as -50.0°C.
During P9-0 the defrost temperature sensor (DTS) reading will be dis-
played on the left display. The right display will show the supply air tem-
perature.
The unit will run FULL COOL for 30 minutes maximum until the DTT is con-
sidered closed. This step may not have to be executed. 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 30 minutes of full cooling.
HTT opens when DTT is considered closed or if return air tem-
perature rises above 248°C (120°F).
Test passes if the DTT is considered open within the 2 hour heat cycle time
limit.
4–51
Sensor Status indicates that a CO
2
sensor will be attempted during P8-1. Once P8-
2
sensor voltage reads within the 0.95 <>1.15Vdc
2
sensor calibration fails.
2
sensor is pres-
2
T-340