Check EXV (EVXV) Superheat
refrigeration
Description
Check EXV (EVXV) Superheat means evaporator pressure fails to drop by 20 psig (1.36 bar) or below 0 psig/bar, or the EVXV appears not to open fully, and Pretrip will fail and display “PRETRIP FAIL AND COMPLETED”.
Activation Conditions
With the unit running in Test #11, after the control system closes the EVXV to 0%, evaporator pressure fails to drop by 20 psig (1.36 bar) or fails to go below 0 psig / bar OR the EVXV appears not to be opening to the full capacity position.
Unit Behavior
Pretrip will fail and display “PRETRIP FAIL AND COMPLETED”.
Reset Conditions
Auto reset if Pretrip is started again 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 Refrigerant Level: Refer to Section 8.7.2. 2. Check System Pressures: Install manifold gauge set to check and compare actual compressor discharge and suction pressures with those shown on the microprocessor display. Suction and Evaporator Outlet pressures must be above 3 psig (0.2 bar.) Refer to Section 8.9.10 for instruction on comparison. 3. Check EVXV a. Visually inspect EVXV for damage. Check to see if coil is seated on valve properly. b. Inspect EVXV coil and wire connections. Verify that there is no physical damage to harness, and no damage, moisture or corrosion in connectors. c. Check EVXV operation. See Section 8.9.7. d. Check basic refrigeration system. Pressures normal. Compressor operation normal. e. Check the EVXV electrical system for good continuity in all circuits from microprocessor to EVXV. f. Inspect component and wire connections. No physical damage to harness. g. Inspect harness connector pins (1-2MSM-6, 7, 8, 9 and 10) (see wiring schematic). Verify that there is no damage, moisture or corrosion in connectors. 4. Check EVOT: Check the sensor. Refer to procedure for alarm 00131 Check Evap Temp Sensor.