Mysterious Freezer Problem

[Vasco]

I have a WAECO (Adler-Barber) tub freezer with a small (like a bar fridge) spill-over fridge. All operated by a Danfoss DB50 compressor. The compressor and brains are five years old. The freezer evaporator plate which goes around three sides of the freezer is 14 years old as are the lines and mechanical thermostat.

Last week I noticed that the evaporator plate only was frosted half way around the plate. The meat in one side of the freezer was defrosting. Also the compressor was working all the time. I assumed that this might be a loss of freon problem and, as I am out in nowhere and have no freon, decided that the only thing I could do was crank the thermostat to the highest and hope for the best. The temperature here varies from 75 to 85 degrees. I rotated the meat to the cold side and filled the non frosted side with rolls of bagels. I also laid a sheet of closed cell foam (about 1/2 inch thick) over the top of the inside of the freezer. It's that blue ground sheet stuff you get at Walmart.

After running the compressor continuously for six days (not a problem as I have lots of power) the other side of the evaporator plate started frosting up. The freezer appears to be working normally now. I have left the setting on maximum and the compressor is going on and off like it used to. It has been working normally for two days now.

Can anybody please tell me what is happening? Or what happened? Happy it is working but mystified. I will get the unit checked when I'm back in the States but would appreciate any input on this. Thanks.

[Ip485]

I would think there is a chance of some contamination in the gas. I had someting similiar. You can try allowing the system to completely defrost, and then start it up again. If the plate freezes evenly there is a good chance this is the reason (but not a guarantee).

If it is (or in any event) it might be worth getting the gas changed and the pressure checked anyway and have a "cleaner" fitted as this will do a good job of removing any contaminants that arent flushed out with the gas change. Sometimes even running some nitrogen through doesnt clean the system.

Often the contamination is water vapour which freezes somwhere in the plate and this accounts for the partial freezing.

[deluxe68]

Originally Posted by Vasco

I have a WAECO (Adler-Barber) tub freezer with a small (like a bar fridge) spill-over fridge. All operated by a Danfoss DB50 compressor. The compressor and brains are five years old. The freezer evaporator plate which goes around three sides of the freezer is 14 years old as are the lines and mechanical thermostat.

Last week I noticed that the evaporator plate only was frosted half way around the plate. The meat in one side of the freezer was defrosting. Also the compressor was working all the time. I assumed that this might be a loss of freon problem and, as I am out in nowhere and have no freon, decided that the only thing I could do was crank the thermostat to the highest and hope for the best. The temperature here varies from 75 to 85 degrees. I rotated the meat to the cold side and filled the non frosted side with rolls of bagels. I also laid a sheet of closed cell foam (about 1/2 inch thick) over the top of the inside of the freezer. It's that blue ground sheet stuff you get at Walmart.

After running the compressor continuously for six days (not a problem as I have lots of power) the other side of the evaporator plate started frosting up. The freezer appears to be working normally now. I have left the setting on maximum and the compressor is going on and off like it used to. It has been working normally for two days now.

Can anybody please tell me what is happening? Or what happened? Happy it is working but mystified. I will get the unit checked when I'm back in the States but would appreciate any input on this. Thanks.

I performed general maintenance on building A/C systems for nearly 10 years on the controls area but I have a general idea about refrigerants. When first installing the system, or doing a leak check, the system is evacuated. Nitrogen may be pumped thru to remove contaminents, but the important thing is to not leave the pipe ends open and expose the internals to water vapor. When you had the compressor installed maybe some shortcuts were taken leaving contaminents in the system. Larger systems have a built-in air dryer/filter but I do not know if yours will have one.

If I were you I would have the existing refrigerant removed, cleaned and the correct amount installed. One thing many installers miss, compressors are shipped with refrigerant already installed. BUT, each installation is different and more refrigerant might be needed based on the piping run or plate size. Do not just add freon without putting gauges on the unit to check pressures.