Check Suction Modulation Valve
refrigeration
Description
Check Suction Modulation Valve means suction pressure fails to drop to the proper range after the control system tries to close CSMV, and Pretrip will fail and display “PRETRIP FAIL IN TEST 10”.
Activation Conditions
With the unit running in Pretrip Test #10, after the microprocessor attempts to close CSMV, the suction pressure fails to drop to the proper range.
Unit Behavior
Pretrip will fail and display “PRETRIP FAIL IN TEST 10”.
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 Wiring to CDP and CSP a. Verify that correct wires are connected to each transducer. Plugs to transducers are the same. The correct wire plug must be connected to the proper transducer. The CDP connector is identified with a red tape band while the CSP connector is identified with a blue band. b. Verify that correct transducer is being used in each position. Mechanical connections to transducers are the same. The Discharge Transducer should have a red marking dot on it. The Suction Transducer should have a blue marking dot on it. 2. Check Compressor Operation: Check compressor operation. If compressor does not pass all tests, repair or replace compressor. Refer to Section 8.8.1. 3. Check Suction Modulating Valve a. Visually inspect CSMV. No damage to valve. b. Inspect CSMV coil and wire connections. Refer to Section 8.9.6. Verify that there is no damage to coil, and no damage, moisture or corrosion in connector. c. Check CSMV operation. Refer to Section 8.9.6. Must perform correctly. d. Check wires from CSMV to microprocessor. Verify that there is no visual damage to wires. Continuity test verifies that each wire is good.(A to 1-2MSM-2, B to 1-2MSM-3, C to 1-2MSM-4, D to 1- 2MSM-5)