Check Supply Air Sensor
electrical
Description
Supply Air Temperature Sensor is out of -53 to +158°F (-47 to +70° C), and the unit alarms and switches to return air control or enters Cargo Protect mode.
Activation Conditions
Supply Air Temperature Sensor (SAT) is not within range of -53 to +158°F (-47 to +70° C).
Unit Behavior
Engine and Electric Operation: If Alarm 00022 Low Suction Superheat is not active: Functional Parameter Temperature Control is set for Supply Air and the setpoint is in the perishable range: Alarm and switch to return air control. If Alarm 00022 Low Suction Superheat is active: alarm and the System will enter Cargo Protect mode. Refer to Section 4.10.2.
Reset Conditions
Auto reset when sensor is in range or, alarm may be manually reset using the display mounted keys or by turning the unit off and then back on again.
Corrective Actions
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 8–1 for chart of resistances for different sensors. 2. Check Sensor Wiring a. Inspect connector pins and terminals at sensor and connector. (See wiring schematic Section 10.3) Verify there is no physical damage to harness, and no damage, moisture, or corrosion in connectors. b. Place the system in PC mode. Refer to Note 2 in Notes Section,. Disconnect sensor from harness. Check for 3.0 ± 0.1 VDC volts at harness plug between pins. This verifies microprocessor output and wiring connections to the sensor.