Sinclair SCV-EB Series Service Manual page 58

5.14 H4 Troubleshooting
5.14.1 Digital display output
5.14.2 Description
 H4 indicates three times L0 protection in one hour
 Heat pump stops running.
 Error code is displayed on the refrigerant system PCB digital tube and user interface..
5.14.3 Procedure
Refer to P6 trouble shooting.
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