Okay simple system to me,
Its something you can't fix TBF, but best option would be to find a good A/C man to help out they usually charge about £50 call out and insist on a nitrogen leak test there is a reason why its loosing gas usually from valve ports.
The ice is no problem its the leak that important.
Who ever you hire to take the job on make sure they
Nitrogen Oxygen Free (Pressure test)
Use a VAC pump to take air and moisture out.
Change the sausage looking item made from copper its called a Spun drier!
Regass R134a
If the leak is on the (heater matrix (rads) looking parts) it might not be worth fixing!
Anywhere there is copper and valves can be braised/replaced to plug up the leak!
I would charge roughly £150 you might get charged more though dark arts
You could just charge it yourself, but it won't last long depends how fast its leaking?
Yeah £45 quid just get a new one this is a domestic jobbie I rarely touch them as I cost too much to help!

I do freeze the odd animal and sometimes they do come back to life Honest, Cryo is a dark art
