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Troubleshooting - Mitsubishi Electric EHSC-VM2B Service Manual

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10-1. Troubleshooting
<Summary of self diagnosis based on Error Codes and Service Procedures>
Present and past Error codes are logged and displayed on the main controller or control board of the outdoor unit.
Please refer to the table below and subsequent explanations to diagnose and remedy typical problems that may occur in the fi eld.
Unit Condition
Reoccurring problem
Non reoccurring problem
Electrical components should only be replaced as a fi nal option. Please follow instructions in Tables 10-4. and 10-5. Error Codes and Inferior Phenom-
ena fully before resorting to replacing parts.
10-2. Test Run
Before a test run
• After installation of outdoor unit, pipework and electrical wiring, recheck that there is no water leakage, loosened connections or miswiring.
• Measure impedance between the ground and the power supply terminal block (L,N) on the outdoor and indoor units with suitable (500V) ohmmeter. Resistance
should be ≥ 1.0MΩ .
• Read the Installation and Operation Manuals fully especially the safety requirements before carrying out any test runs.
10-3. Malfunction diagnosis method by main controller
If during start up or operation a malfunction occurs the error code screen may be displayed on the main controller.
The error code screen shows the following; code, unit, ref. address, and telephone number of installer (only if previously entered by the installer)
Please not in the case of some malfunctions an error code is not generated please refer to table 10-5. for more details.
To reset
1. To reset the main controller press F4 button (Reset).
2. Then press F3 (Yes) to confi rm.
Error Code
Use table 10-4. "Self diagnosis and action" to identify fault and correct.
Not Displayed
Use table 10-5. "Troubleshooting by inferior phenomena" to identify fault and correct.
1. Check temporary causes of defects such as the operation of safety devices on the re-
frigerant/water circuit including compressor, poor wiring, electrical noise etc. Re-check
the symptom and the installation environment, refrigerant amount (Split systems only),
weather conditions at time of fault etc.
2. Reset Error code logs, Service the unit and restart system.
Not Logged
1. Recheck the abnormal symptom
2. Identify cause of problem and take corrective action according to Table 10-5. "Trouble-
shooting by inferior phenomena"
3. If no obvious problem can be found continue to operate the unit.


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