Check Evap Temp Sensor
refrigeration
Description
Evaporator outlet temperature sensor is out of range -53 to +158°F (-47 to +70°C); the unit gives alarm only and calculates EVXV superheat using SAT or DTT if 00123 is active.
Activation Conditions
Evaporator Outlet Temperature Sensor (EVOT) is not within the range of -53 to +158°F (-47 to +70°C)
Unit Behavior
Alarm only and superheat for EVXV will be calculated using SAT or DTT if alarm 00123 Check Air Supply Sensor is active.
Reset Conditions
Auto reset when EVOT 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 there is no damage to sensor, and no damage, moisture, or corrosion in connector. b. Check EVOT resistance. Refer to Note 3 in Section 7.2. Should be 10,000 Ohms @ 77°F (25°C.) See Table 1–3 for complete table of temperatures and resistance values. 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 volts at harness plug between pins. This verifies microprocessor output and wiring connections to sensor. 3. Check Airflow Through Evaporator Coil/Section a. Inspect coil. Ninety percent or more of the coil surface must be undamaged. Coil must be clean. b. Check coil airflow (with unit running). Even airflow through the entire coil. No “dead” spots. c. Check return air bulkhead, air chute. Verify good air flow and make sure return air not restricted. Air chute should be in good condition.