62-11785 7–38
00131 CHECK EVAP TEMP SENSOR
• ACTIVATION: Evaporator Outlet Temperature Sensor (EVOT) is not within the range of -53 to +158°F
(-47 to +70°C).
• UNIT CONTROL: 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 man-
ually 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 appropriate modes to see
if any active alarm occurs. Continue with the steps below as necessary.
CORRECTIVE ACTIONS:
1. Check Sensor
a. Inspect sensor & 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 8–3 for complete table of temperatures and resistance values.
2. Check Sensor Wiring
a. Inspect connector pins & terminals at sensor and connector 2MM. (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 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). Verify even airflow through the entire coil. No “dead” spots.
c. Check return air bulkhead and air chute. Verify good air flow and make sure return air is not
restricted. Air chute should be in good condition.
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