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00131 Check Evaporator Temperature Sensor
• ACTIVATION: Evaporator Outlet Temperature Sensor (EVOT) is not within the range of -53 to +158°F
(-47 to +70°C)
• UNIT CONTROL: Engine and Electric Operation: Alarm only and superheat for EVXV will be calculated
using SAT or DTT if alarm 00123 Check Supply Air Sensor is active.
• RESET CONDITION: Auto reset when Evaporator Temperature 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.
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 Evaporator Temperature Sensor resistance. (Refer to Note 3 in Notes Section) 10,000 Ohms
@ 77°F (25°C.) See Table 8–5 for complete table of temperatures and resistance values.
2. Check Sensor Wiring
a. Inspect connector pins and terminals at sensor and connector
1-3MSM-5 and 28
. (See wiring
schematic Section 10.2) 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 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.
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