Carrier TRANSICOLD VECTOR 8100, Operation & Service Manual, Page: 147 / 294

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00022 LOW SUCTION SUPERHEAT
• ACTIVATION: Alarms 00127 CHECK SUCTION TEMP SENSOR and/or 00131 CHECK EVAP TEMP
SENSOR are not active and Compressor suction superheat (Compressor Suction Temperature (CST)
minus saturated temperature for Compressor Suction Pressure (CSP) is less than 8°F (4.4°C) for more
than 3-4 minutes.
• UNIT CONTROL: Refrigeration system shutdown and alarm with PSCON still energized.
• RESET CONDITION: Auto reset after 15 minutes, 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 appropriate modes to see
if any active alarm occurs. Continue with the steps below as necessary.
CORRECTIVE ACTIONS:
1. Check System Pressures
a. Check Suction and Evaporator Pressure reading at the compressor. While the compressor is
running and the SMV is greater than 70% open, verify evaporator and suction pressure read within
3 psig of each other, with evaporator pressure slightly higher than suction pressure. If not, check
transducers. Refer to
Section 8.7.11 .
b. Install manifold gauge set and check and compare compressor discharge, suction and evaporator
outlet pressure to the Unit Data readings. Refer to Section 8.7.11 for instruction on comparison.
2. Check Evaporator Section - Check evaporator section, return air bulkhead, air chute, and the evapora-
tor coil (for cleanliness and airflow). Refer to Section 9.2.10 .
3. Check Suction and Evaporator Temperature Sensors
a. Check Evaporator and Suction temperature sensor insulation integrity, and make sure insulation is
properly installed. Repair or replace any insulation if required. Loose or missing insulation will
cause inaccurate refrigerant temperature readings.
b. Inspect sensor & connector. Verify there is no damage to sensor. Verify there is no damage,
moisture, or corrosion in connector.
c. Check 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.
4. Check Expansion Valve (EVXV)
a. Visually inspect valve. Check that the coil is seated properly.
b. Check operation of valve. Refer to Section 8.7.8 .
5. Perform Pretrip Check - Clear Active Alarm list, then run Pretrip & check for any new alarms. Any active
alarms must be corrected and cleared before proceeding.