Hi, my first post here. I have searched the forum but don't seem to be able to find anything the same. I have an issue with a unit which has been working fine since June 2021. Cooling and heating until a couple of weeks go when we dipped in to -3 and and had freezing fog. Now the unit will only run for about 10 minutes before the coils freeze up outside. Any ideas, has the cold weather created a problem with one of the refrigerant lines, i.e. a leak in extended pipework joint? I still get heat from it before it ices up. Or is this a problem with a valve or defrost sensor?
Please see pictures.
Any information as to the possible cause would be brilliant.

Many thanks

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