I have a Marvel Ice Maker that is about 7 years old. Forever is has had a small leak in the freon core somewhere. As long as it runs continiously it will make ice but if it is turned off it will loose pressure and not. I had a refirgerant filler valve installed by a local repairman the first time this happened. It has gone down a couple time since then and I just shot in some fresh refrigerant. This last time I bought a kit with a pressure guage. When I hooked it up, and opened the valve on the low pressure line the guage shot up into the red. This is a kit for filling auto a/c but I felt is work just as well here. I then just removed the filler and discharged some of the freon until it came down into the blue range. It still does not make ice, in fact it seems to be generating a lot of heat in the ice bin. Can any one out there give me a hint.