I have H42 error on my LA-MI heat pump. What does this mean?

Applicable to models:  LA6MI, LA9MI, LA12MI, LA16MI


Issue:  Error code H42 shown on the display. No heat, compressor is stopped.  


What this means: Compressor low pressure abnormality. 

Action: End user should make sure there are no obstructions or debris restricting the air movement around the heat pump outside. 

If air is restricted or recirculating due to obstructions, then insufficient thermal energy from the air will be captured and the heat pump will fault on H42 fault. If there were obstructions, clear them, then try to clear the error as follows:

If that does not solve the issue, until an engineer can attend, it should still be possible to use the electric backup. To enable the backup search for the guide "How to I switch on the backup on the LA-MI heat pump?" on the GDHV Help Centre.

If the error persists an engineer visit would be needed.
Heat pump must be safely isolated from mains supply before carrying out any work!

Only F-GAS qualified engineers are legally allowed to work on the system if they are leak checking or changing refrigerant components!

Engineer to follow the flow chart:

Malfunction Decision Conditions:

During operation of heating and after 5 minutes compressor ON, when outdoor pipe temperature below -29°C or

above 26°C is detected by the outdoor pipe temperature sensor.

Malfunction Caused:

1 Dust accumulation on the outdoor unit heat exchanger.

2 Air short circuit at outdoor unit.

3 2 way valve partially closed.

4 Faulty outdoor unit fan motor.

5 Refrigerant shortage (refrigerant leakage).

6 Clogged expansion valve or strainer.

7 Faulty outdoor pipe temperature sensor.

8 Faulty outdoor unit main PCB (fridge main). 

Require additional help? Please follow link below


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