Check Suction Temp Sensor
refrigeration
Description
Compressor Suction Temperature Sensor is out of -53 to +158°F (-47 to +70° C.), and the unit alarms and switches superheat control to the supply air temperature sensor.
Activation Conditions
Compressor Suction Temperature Sensor (CST) is not within the range of -53 to +158°F (- 47 to +70° C.)
Unit Behavior
Engine and Electric Operation: Alarm only. Control of Superheat will switch to supply air temperature sensor.
Reset Conditions
Auto reset 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 there is no damage to sensor, and no damage, moisture, or corrosion in connector. b. Check sensor resistance (Refer to Note 3 in Notes Section.) 10,000 Ohms @ 77°F (25°C.) See Table 8–1 for complete table of temperatures and resistance values. 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.