I have H23 error on my LA-MI heat pump. What does this mean?

Applicable to models:  LA6MI, LA9MI, LA12MI, LA16MI


Issue:  Error code H23 shown on the display. No heat, compressor is stopped.  


What this means: Refrigerant liquid temperature sensor defective or disconnected.

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.


Action: Engineer visit needed. Heat pump must be safely isolated from mains supply before carrying out any work!  Engineer to check the sensor cable connection CN-TH1 onto the main water PCB & check probe resistance vs known temperature, following the flow chart:

Location of CN-TH1 plug on Main water PCB (LA6MI / LA9MI):

Location of CN-TH1 plug on Main water PCB (LA12MI / LA16MI)

Possible parts, depending on engineer diagnosis: 

• Temperature probe (one of three probes all on same loom/plug, the other two probes are water flow & return temp probes, all on CN-TH1 connector plug going to the main Water PCB). 

LA6MI / LA9MI part: X-2517001
LA12MI / LA16MI part: X-2511054

• Main Water PCB (part number depends on model of heat pump)

LA6MI part: X-2511031
LA9MI part: X-2511039
LA12MI part: X-2511051
LA16MI part: X-2511058

Require additional help? Please follow link below


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