Check Ambient Air Sensor
electrical
Description
Ambient air temperature sensor is out of range -53 to +158°F (-47° to +70°C); the unit alarms and uses 122°F (50°C).
Activation Conditions
Ambient Air Temperature Sensor (AAT) is not within range of -53 to +158°F (-47° to +70° C).
Unit Behavior
Alarm and a value of 122°F (50°C) will be used for any calculations.
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, then back on again.
Corrective Actions
1. Check Sensor a. Inspect sensor and connector. Verify no damage to sensor. Verify no damage, moisture, or corrosion in connector. b. Check sensor resistance. (Refer to Note 3 in Section 7.2) 10,000 Ohms @ 77°F (25°C). Refer to Section 1.9.21 for chart of resistances for different sensors. 2. Check Sensor Wiring a. Inspect connector pins and terminals at sensor and connector 2MM. (See wiring schematic Section 1.) 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 Section 7.2. 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 the sensor.