Information Needed for Refrigerator Decision

[ncrowley]

I am having problems with my Dometic refrigerator. It is great at keeping everything cold and frozen, but there is frost build up in the refrigerator and freezer. In the refrigerator, the fins frost up badly so I need to remove the frost every 5 to 7 days. The frost is building up on the fins on the side where the door opens. In the freezer, the frost is building up where the door opens as well.

I have the battery powered fan to circulate the air and it has not helped. I did the dollar bill test on the door seals and they seem to be fine. I was going to replace the door seals but they do not make them anymore and I would need to replace the doors.

First question: if I keep the refrigerator, should I replace the doors? Is there something else that can be wrong? It is the "pizza" refrigerator with the zig zagged doors.

Second question: I am taking the coach back to Newmar for some updates and I could replace it with a residential refrigerator. However, there is no room to add batteries and I have 4 house batteries. Newmar says that they would not run it off the inverter and it would stay cold when we are traveling. We rarely dry camp - we have dry camped once in the 3 years we have owned it. But I worry about the refrigerator staying cold while on the road for 8 hours. Would I need to run the generator for a while during the day, for example, when having lunch?

Third question: How long do the Dometic refrigerators typical last? The one I have is 12 years old now. Should I be worried about it having to replaced sometime soon?

Thanks for your help.

[JimM68]

I also have a 1402, that I've been struggling with for a while.

Mine frosts up in both the freezer and the fridge, worse in the freezer.
And it heats up excessively while travelling.

Just FYI's...
The 1402 has 4 thermisters, one on the freezer fins, one in the freezer, one on the fridge fins one in the fridge. They are not adjustable.

The led display shows "an imagination" of the temp of food in the fridge and the freezer. We can see when it is warming up. Normal is 1-3 degrees in the freezer, 32 to 34 in the fridge.

It controls the temp in each box separately. The freezer temp is controlled by how often and long the cooling unit is heated. The fridge is then warmed with the defrost heater to hold it's correct temp, supposedly it would otherwise run too cold.

The 1402 has a factory fan in the fridge, located at the top rear.
And one in the freezer, in a complicated ductwork intended to fully circulate the air top to bottom and force feed it thru the freezer's cooling fins, which are mostly sealed and invisible.

The fans are controlled by the door switches, only run when the doors are closed.

It has a diagnostic test mode. Detailed in the book. Hold down set then turn it on for diagnostic mode. Press set to step thru the various tests. All in the book. You can check the door switches, turn on the AC or gas, turn on any of the 3 defrost heaters, etc. You can test everything.

It has a clock. That needs to be set, once unless power is removed for a long period of time. it flashes -- -- if the clock needs to be set.

It defrosts every night at midnight. A complicated process, with the bottom line that it has a set amount of time to complete, and it heats the cooling fins to 40 degrees for a set period of time. Supposedly it will show an error if it is unable to get the fins to 40 degrees in the proper amount of time 2 nights in a row.
Mine has never showed this error, tho it doesn't appear to successfully defrost.

I have a real love/hate relationship with this thing.

It is WAY more complicated than your typical absorption fridge. I WISH i could control the temp by sliding a thermister up the fins, and defrost it with a hair dryer once a month...

[FormerBoater]

17 years for the Dometic side by side in the Eagle.

Never ceases to amaze me with the amount of ice the ice maker produces.

[Jim]

The longest I've heard of an absorption refer lasting was 73 years. In a cabin. Can't remember for sure which brand but it might have been a Dometic.

If you have fans blowing on the fins in the refer portion, they tend to keep the fins frost free, here's how I did it...

Adding Refer Fans

[dougrainer]

Dutchstar02 wrote:
The thermistor turns off the fridge when it gets cold. If it never shuts off then the defrost cycle won't work and you get a buildup of ice on the fins in the fridge. To check the thermistor have the fridge running on propane. Put the end of the thermistor in a glass of ice water. If it's working properly, it will shut off the gas supply. It's easier to test on propane because you can't tell if it's off when it's running on electric. If the thermistor is working then it's likely a circuit board.

FYI, The temp of the evap fins will ALWAYS be 10 degrees colder than the items in the refer. That means, on a correctly operating RV refer, the fins will ALWAYS be colder than 32 degrees. Ice/Frost will happen on the fins because the interior humidity will have its moisture form on the fins due to that colder temp. THAT is a normal occurrence. Unlike Norcold Temp Thermisters, I have never really found a Dometic Thermister fail. Now, your test is invalid. The Thermister senses LOWER temps than 32 degrees(Temp of icewater). Doug

[Ivylog]

Yes it's working correctly. With winter coming on and lower humidity the icing up may get better. The little double fan I posted above does a good job of keeping the ice off.

[ncrowley]

I tested the thermistor and it is working fine. I put it in ice water and after a little bit, it stopped making noise. Then I took it out of the water and let it warm up, and after a little bit, it started making noise again. Doesn't that main the board is OK since it is turning on and off?

[ncrowley]

Thanks for all the information. The model number is NDR1402. I did the dollar bill test and compared the resistance when I pull the bill out with my new refrigerator in the house and they seem comparable, so my assumption is the door seal is OK. It sounds like I have a thermistor problem or a circuit board problem. It seems the defrost cycle is not running at all if I have all that frost build up.

The drain lines seem to be working fine and look OK.

I will test the thermistor with the ice of glass water and see what happens.

[Dutchstar02]

The thermistor turns off the fridge when it gets cold. If it never shuts off then the defrost cycle won't work and you get a buildup of ice on the fins in the fridge. To check the thermistor have the fridge running on propane. Put the end of the thermistor in a glass of ice water. If it's working properly, it will shut off the gas supply. It's easier to test on propane because you can't tell if it's off when it's running on electric. If the thermistor is working then it's likely a circuit board.

[Ivylog]

X2 on what Doug said instead of what Newmar told you. I used one of these that clips on the fins and by moving it everyday to a new location it defrosts the fins. For less than S17 start with one of them. When your unit stops working well, you might want to go residential.

[dougrainer]

-Gramps- wrote:
Frost will build up on the fins if you have a bad thermister. Its that thing with wires attached to the fins.

Really? EXPLAIN why you think this is. Doug
PS, it is NOT true.

[-Gramps-]

Frost will build up on the fins if you have a bad thermister. Its that thing with wires attached to the fins.

[pianotuna]

Hi,

I added a fan that sucks air directly from the fins. No more frost build ups, and quicker cooling too!

[deandec]

Third question: How long do the Dometic refrigerators typical last? The one I have is 12 years old now. Should I be worried about it having to replaced sometime soon?

I do not know. My Dometic side by side is almost 21 years and 97,000 miles old. It seems to work fine.

[Executive45]

Frost will build up because of air entering the box and/or freezer. This can be caused by opening the doors too much, too often or as Wolfe stated, a defective drain line. I can't help you with the first one, that's on you. As for the drain line, that is the 1/4 line running out the back of the box into a small metal cup. Remove the outside access panel and find that line. It runs from the cup to the plastic tray that runs under the cooling fins inside the box. Make sure the one end has NOT come loose from the tray and look for a small plastic plug in the end that goes into the tray. This plug MUST be in place to keep air from getting into the box thru the hose. Finally, inspect the hose for brittleness. If it's brittle at the exposed end, then it's most likely brittle all the way up. This causes the hose to leak which will cause your problem....Dennis