60
6. Troubleshooting
Troubleshooting must be performed only by personnel certified by Mitsubishi Electric.
[1] Diagnosing Problems for which No Error Codes Are Available
If a problem occurs, please check the following. If a protection device has tripped and brought the unit to stop, resolve
the cause of the error before resuming operation.
Resuming operation without removing the causes of an error may damage the unit and its components.
Problem
Check item
Cause
Solution
The unit does not
operate.
The fuse in the control box
is not blown.
The power lamp on the
circuit board is not lit.
The main power is not turned on.
Switch on the power.
The power lamp on the
circuit board is lit.
The pump interlock circuit is not
connected.
Connect the pump interlock circuit wiring to the
system.
The flow switch wiring is not connected. Connect the flow switch wiring to the system.
The fuse in the control box
is blown.
Measure the circuit
resistance and the earth
resistance.
Short-circuited circuit or ground fault
Resolve the cause, and replace the fuse.
Automatic Start/Stop
thermistor has tripped.
Water temperature is high.
Normal
Water temperature is low.
The setting for the automatic Start/Stop
thermistor is too low.
Change the setting for the automatic Start/Stop
thermistor.
The unit is in
operation, but
the water does
not heat up.
Water temperature is low.
The water inlet/outlet
temperature differential is
normal.
The water-heating load is too high.
Install more units.
Low refrigerant charge due to a leak.
Perform a leakage test, repair the leaks, evacuate the
system, and charge the refrigerant circuit with
refrigerant.
The water inlet/outlet
temperature differential is
small.
LEV fault in the main circuit
Replace the LEV in the main circuit.
Compressor failure
Replace the compressor.
High pressure is too high, or low
pressure is too low.
Operate the units within the specified pressure range.
Water temperature is high.
Water flow shortage
Increase the water flow rate.
Problem with the external devices
Repair the devices.
WT08219X05.book 60 ページ 2018年10月1日 月曜日 午後7時47分
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