In the past I mainly worked on washers and dryers in a shop. I am doing service now on used appliances. Covering the warranty. I have worked on a fair share of refrigerators, just not the sealed system. Question? I had an older top and bottom refrigerator that was iced up. After I manually defrosted it with a hair dryer I found a clogged drain. I noticed as I was putting it all back together. I thought it was the evaporator fan so I stopped it. That's when I noticed the evaporator itself was loud. Making a noise. Only thing I can imagine is the system was overcharged in the shop and what I am hearing is liquid Freon going through the evaporator coil. I guess the noise resembled a small stream flowing. Any ideas on what I'm hearing?