Dehumidifier READ FULL DETAILS (Mansfield NG19)

READ FULL DETAILS NEEDS REPAIRING/RE-GASS
Only around 3 years old.
It switches on
Motor runs
Programs change all as they should
BUT !!! it does not defrost so it ices up.
I've cleaned all the filters and drip try but I think it needs re-gassing.
I'm pretty sure I've got the manual for it too.
Maybe someone can sort it out if they know what they are doing.