7–53 62-12259
00122 Check Return Air Sensor
• ACTIVATION: Return Air Temperature Sensor (RAT) is not within range of -53 to +158°F (-47 to +70° C).
• UNIT CONTROL: Engine and Electric Operation:
• If alarm 00123 Check Supply Air Sensor is not active: Alarm and switch to supply air control.
• If alarm 00123 Check Supply Air Sensor is active: Alarm and the System will enter Cargo Protect
Mode. Refer to Section 4.10.2.
• RESET CONDITION: Auto reset when sensor is in range or, alarm may be manually reset using the
display mounted keys 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 appro-
priate modes to see if any active alarm occurs. Continue with the steps below as necessary.
1. Check Sensor
a. Inspect sensor and connectors. Verify there is no damage to sensor, and no damage, moisture, or
corrosion in connectors.
b. Check sensor resistance. (Refer to Note 3 in Notes Section) 10,000 Ohms @ 77°F (25°C). Refer to
Table 8–5 for chart of resistances for different sensors.
2. Check Sensor Wiring
a. Inspect connector pins and terminals at sensor connector
1-3MSM-15 and 27
. (See wiring
schematic
Section 10.2
) Verify there is no physical damage to harness, and no damage, moisture,
or corrosion in connectors.
b. Place system in PC Mode. Refer to Note 2 in Notes Section Disconnect sensor from harness. Check
for 3.0 ± 0.1 VDC at harness plug between pins. Voltage should be 3.0 ± 0.1 VDC volts at harness
plug between pins. This verifies microprocessor output and wiring connections to sensor.
To Next Page
Loading...
