Even a trained technician that knows what he's doing must be very cautious when replacing the substances required to make these things work. They must put in the proper amounts of ammonia and water with a little chromate as a wetting agent into the system, then pull a very deep vacuum before pressurizing it with hydrogen. All those ingredients but the water hazardous materials and have to be handled with the utmost care. One spark and you could lose an arm or worse - many have. That's why you won't find just anyone repairing these refrigerators. Leave it to the shops that specialize in this work and be thankful for them.