Spot on, I did the same a few yrs ago, the gas was a lot cheaper then! About £80 a bottle now. I also have a set of guages on board and some solder type 1/8” ? access valves. For a vacuum pump I used an old mains fridge compressor, soldered on an access valve. Works great. For the tooth suckers, the amount of gas in our systems is just a sparrow fart in the great scheme of things! And cynical old moi noted that when the tree huggers were whining on and the uk had mountains of fridges that couldnt be “recycled” that the R12 that was being recovered was being shipped to India and China! I wonder what for? plus I never got a satisfactory answer as to how heavier than air freon got to the ozone layer to allegedly destroy it! And of course the hilarious stories about our EU masters trying to get car manus to use highly flammeable propane or some such in acs in cars and the german manus telling them to go swivel, allegedly!Very possible. You need a manifold with pressure gauge, hoses and valves, the gas itself (probably R134a, but you've gotta check - usually an obvious sticker on the pipes), a tap valve for the gas bottle and typically a vacuum pump, all with matching connectors.
You also need to fix the leak. Ours was in the rubbish quick connect couplings that are the main downside of kit fridges. In many, if not most cases of boat fridges leaking or having blockages, it seems to be caused by those. If you do this, you inevitably need the vacuum pump to evacuate the system, as the couplings needed removing, cleaning up crumbling sealant (that was intermittently blocking the capillary pipe) and careful resealing. We used a bicycle pump to blow the pipes through and clear them of any sealant crumbles.
The parts are all easy to get apart from the gas. I've got lucky and scored a bottle of 900g of pure R134a (no oil) on eBay. The car airconditioning mixes with oil in them can supposedly be used too, by keeping the bottle upright (valve on top), so the oil remains behind in the bottle, but I didn't not need to resort to this.
All in all the parts were around £140, which was less than a single call-out charge to regas the thing, not including labour to actually fix the couplings, which most refrigeration engineers won't do anyways, they'll just want to sell you a new kit fridge for £600 or thereabouts.
Best do it outside the UK to avoid hobby lawyers chasing you down ;-) Read more about R134a: https://en.wikipedia.org/wiki/1,1,1,2-Tetrafluoroethane
It is very satisfying to hear the boiling gas burbling away in the evaporator and feel it get cold again after you've successfully repaired your fridge!
+1 - we work on larger systems at < 5 torr, but let's not split hairs eh. I reckon this old compressor at best would achieve around 100 torr vacuum. Not much moisture flashing off there, then the user wonders why there is reduced gas flow and utterly fail to understand the effect of moisture frozen at the outlet from the capillary, but does note the frozen plate, fully charged system and no leaks.
.I know its about “boiling” off water. I was repairing stuff like this back in the 80s as part of my game. According to my professional guages it did. 1 bar is only 15psi so atmospheric pressure, pull it below 0 and you have that.
+1 if we could all use an old compressor as a Vac pump believe me we would. But Vacuum Pump Oil is snake oil in its finest form. You can use basic engine oil in a vac pump without any problems at all (not in the fridge compressor). The big issue with fridge 'kits' is the quality of the joints, always. Brazed joints are always superior, but pre-charged units will then require a vac and regas.
