4–57
T-372
P7-1 High Pressure Switch (HPS)
Closing Test
If return temperature greater than -2.4°C, set setpoint to -5.0°C, else set
setpoint to -30°C. Restart unit according to normal startup logic. Run unit
normally for 120 seconds.
The test passes if the high pressure switch closes within 75 seconds after
end of Test 7-0, else the test fails.
Test P7-0 must pass for this test to execute.
P8 Tests - Perishable Mode Tests:
Pre-trip tests P7-0 and P7-1 must have passed or have been
skipped for these tests to execute.
P8-0 Perishable Mode Test
If the control temperature is below 15.6°C, the setpoint is changed to
15.6°C, and a 180 Minute timer is started. The control will then be placed
in the equivalent of normal heating. If the control temperature is above
15.6°C. at the start of the test, then the test proceeds immediately to test
8-1. While in test 8-0 the right display will show the value of the control
temperature.
The test fails if the 180 Minute timer expires before the control temperature
reaches setpoint - 0.3°C. If the test fails, it will not auto-repeat. There is no
pass display for this test. Once the control temperature reaches setpoint,
the test proceeds to test 8-1.
P8-1 Perishable Mode Pull Down
Test / eAutoFresh CO
2
Sensor Calibration
Control temperature must be at least 15.6°C (60°F).
The setpoint 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 setpoint.
The test passes if the container temperature reaches setpoint 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
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.
Table 4–9 Controller Pre-Trip Test Codes (Continued)
