T@B 320 CS Refrigerator Issues

Mickerly

We have a 2018 320 CS we purchased last Winter. The refrigerator is a DC powered Norcold NR751. On our outing in May, setting 3 kept the temperature at 40ish, but we made gallons of condensation. Our next trip, the refrigerator ran constantly and never got below 50°F. When we got home, I started looking for problems.

The door seal looked okay. It was a little hard but serviceable. The bottom rail of the frame was bumpy and rusted. The condensation caused rust that prevented the door seal from closing at the bottom. Of course, more air leak means more condensation, more rust and so on. Between rust remover and sanding I got back to bare metal and a smooth surface.

I noticed the joints between the bottom rail and the sides of the frame are too deep for the door seal to block. These two gaps were probably the original source of the condensation. I filled the gaps with epoxy, sanded them smooth and repainted the frame. Also, the plastic liner and the metal frame are not sealed together. A small amount of silicon filled that gap.

On a second note, behind the refrigerator, the panel is cut away to make more room for the depth of the refrigerator. This means one thin sheet of birch is between the refrigerator compressor and our heads while sleeping. Yes, it is loud. I added some thick foam floor padding behind the refrigerator. Next trip we’ll see if it works.

Dutch061

Was there any corrosion on the refrigerator tubing around the compressor? This has been observed by many including myself and can be cleaned off using a mixture of salt and vinegar. Make sure to neutralize with baking soda and water. Also, looking at refrigerator from the back end, on the right side there are 2 tubes. One is small and the other is tiny and goes into an area covered with black foam that is tied on with plastic ties.

There will likely be corrosion there also. 

If you cut those plastic ties to remove the foam wrap, be super careful as the tiny tube (also referred to as a capillary tube) is wrapped around the bulb (filter drier) and you can easily cut the capillary tube.

Unfortunately, I found this out the hard way. Amazon sells a NR751BB exactly like you have but they are $851.00, as I just bought one for our 2020 400 BDL after I cut the capillary tube. The new out of the box refrigerator already had some green on it.

I suspect that on a 2018 that the corrosion may have gotten the better of the tubing and weakened it to the point of failure. You may have lost the refrigerant, hopefully not. There is a high temperature cut out that prevents the compressor from operating if the temperature of the power module is over 212 F.

Also, the idea of foam for noise is good but the compartment is likely not deep enough to allow for proper air flow with it in there. I made a modification on our 2020 400 BDL in an effort to reduce the heat in the compartment the refrigerator is in. We leave in a few days for 6 weeks, I will be able to report back if that was worth the time, effort, and a new refrigerator in the process. 

I am attaching the manual for the NR751 incase you don't have one.

Brad

P.S. Here are a couple photos of the corrosion I saw

Mickerly

I looked through the manual and maintenance material before I started. It appears the refrigerator is designed for a zero space enclosure. That's why it draws air from the front, under the unit and exhausts out the front. I didn't find any corrosion in the compressor area. Just a lot of rust in the front.

Mineral Wells State Park at over 100°F, greater than 70% humidity, and full sun for our test run. In the August heat of west Texas, the refrigerator worked great. If it works here it will work anywhere. I used a remote thermometer to monitor the temperature without having to open the door.

We pre-cooled the refrigerator before leaving home. In the two hour drive on Friday afternoon, we lost 5° with the refrigerator off. That’s better than we have noticed in the past. Once in camp, a setting of slightly more than 3 kept the refrigerator between 34 and 42°. Part of that time was in direct sun. We tried the clam-shell open fully, open 2 inches and completely closed. The temperature changed less than 3° between all three positions. Which position that worked best depended on the sun. In direct sun into the kitchen, the refrigerator worked better with the shell closed. The insulated cover with restricted air flow was better than free air and direct sun on the black refrigerator door. At night it didn’t make any difference between the three positions. The temperature in the kitchen did rise 7° if kept closed for more that 6 hours. Keeping the kitchen end of the trailer in the shade appears to be the most important variable.

For three days, there was not a drop of condensation. No more air leaks.

The noise of the air conditioner prevented us from hearing the refrigerator running at night. It will be a couple of months before we can figure if it is more quiet at night.

For us, the refrigerator is too small for a complete weekend of food. So, it won’t replace our ice-chest. It will reliably hold items we don’t want to get wet. It will hold temperature for short distances, around 2 to 3 hours, when turned off. It cycles much less than it did, so I'm comfortable running it while being towed.

We have learned some tricks. If you put a couple of blocks of blue ice in the freezer or keep it most of the way full of cold food, the temperature drop from opening the door is significantly less. By the way, the blue ice stayed hard all weekend. Any bags or labels that block the airflow between the food items will hinder cooling and cause hot spots. So, don’t stuff a bag of drinks in the refrigerator. Drinks only, no bags. And, leave a little space for air flow around items.

The T@G with a built-in refrigerator and the T@B 400 with a closet have very similar Norcold refrigerators. If you’re having condensation issues or it seams to be running too much, look at the bottom of your refrigerator. I bet the gaps between the bottom rail and the sides are too deep for the door to seal.

Dutch061

I understand that it is designed for a zero space enclosure, but anything you can do to promote cooling of the enclosure should aid in improving performance and reducing the "time per hour" that the refrigerator is running. 

Glad you sorted it out and that it is working to your satisfaction. Life is always better when things work!

Brad

Mickerly

Agreed