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Old 01-08-2020, 05:29 PM   #1
Loneoak
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Dometic 1350 temperature fluctuations

The temperature fluctuates wildly in our fridge. Sometimes it is 37 (my happy place), and then a few hours later it goes up to 44. (This happens without opening the fridge). We have friends who have an identical trailer (same model and year). They are having the same problem. Both of us are in Florida.

We called a mobile RV repair. The guy came and hot wired the fan, making the fan on all the time. He figured maybe it was the switch. This did not solve the problem. I got up one morning and found it at 40, and this is when it was a cold night. Normally the fridge is at its coldest first thing in the morning.

He also left us a spare thermistor, and showed DH where to plug it in. DH and friend tried, but they did not know how to thread it through to the fridge, so they gave up on that. We called them back.

They showed up while we were out, and the guy plugged in the new thermistor. The sensor end was then outside the fridge. Of course, the temperature shown on the fridge went up into the 50s, and the actual temperature in the fridge got into the "too cold" category. I have a fridge thermometer in it.

Does anyone have any idea what might cause wild temperature fluctuations like that?
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Old 01-08-2020, 08:44 PM   #2
tspoon
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I put two fans on the fins inside the fridge. I have 2015 305rl with 1350 fridge. That fixed my problem with temp going up.
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Old 01-09-2020, 04:59 AM   #3
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I have one in the fridge and our friends don’t have one at all.
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Old 01-09-2020, 08:02 AM   #4
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My 2014 has the RM1350 fridge. No temp fluctuations. Iíd start by checking the door seals and see if there is a gap anywhere... pay close attention to the lower seal area. A dollar bill should stay tight in the door seal with doors closed ... if not you need to address that issue first.

Iíd also remove the outside upper and lower vent covers for the fridge and blow that area out with an air compressor. Use low pressure..about 25 psi...gently blow out the condenser coil area located at the upper vent.

Make sure the baffle is still in position at the upper vent area.

Mine stays around 34 in 100 degree temps
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Old 01-09-2020, 10:02 AM   #5
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Assume you have the installation manual. If you compare what is behind the top outside vent, does it match what is in the manual? Is the bottom airflow metalwork meeting the requirements and is the top metalwork meeting install requirements?
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Old 01-09-2020, 10:09 AM   #6
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We also have the RM1350 and we are also in Florida. Ours runs between 35 and 39, and temperature setting is on three. I have two 4 inch AC fans installed in the bottom vent outside, facing upward, to help push the heat out. The fans at the outside top vent (noisy ones) seldom kick in as a result. Defrost mode will cause some temp variances; putting anything warm in the frig will cause the temp to jump, we either stick the warm items in the freezer for 15 minutes or so, or stick in our bar frig outside.
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Old 01-12-2020, 08:24 AM   #7
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I am wondering if this defrost mode could be the culprit. Last night, it was at 37, then it suddenly started going up to 45 before DH went to bed. He mistakenly set the temperature to 2, from 3, not realizing that lower numbers mean less cold. I got up early to find the fridge at 48, the set it to 4. I also turned the fridge off and then on again after a few seconds. None of this made a difference. A couple of hours later, the temperature started to drop again.


This is after 3 days of the temperature being perfect. I had it set on 3 as the outside temperature is quite warm right now here in Florida.


Does anyone know how this automatic defrost works, how often it does its thing, and if these temperature fluctuations are normal? I just don't like the temperature going into the high forties and low fifties. I am concerned about food safety.
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Old 01-12-2020, 08:49 AM   #8
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You should be concerned with those temps. The fix is adding fans to move more air through the upper outside fins and out the upper vent. It has been documented here by many of us. Ours went from being set on 5 (coldest) and varying temps up to 50 to being set on 3 with steady temps in the mid 30's.

Nearly all RV fridge problems are the result of poor installation by the RV manufacturers. They simply do not adhere to clearance and baffling to move
air across those outside fins and out the upper vent.
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Old 01-12-2020, 11:48 AM   #9
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Have you tried putting a thermometer inside your fridge to compare it to whatever you are currently monitoring? You may be chasing a ghost. Or ... does the inside really feel not so cool? We keep a small battery powered fan inside the fridge to move air around ... it helps even out temps somewhat. I added the ARP unit years ago. It makes the outside fans come on sooner and stay on longer.
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Old 01-12-2020, 12:02 PM   #10
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Quote:
Originally Posted by dieselguy View Post
Have you tried putting a thermometer inside your fridge to compare it to whatever you are currently monitoring? You may be chasing a ghost. Or ... does the inside really feel not so cool? We keep a small battery powered fan inside the fridge to move air around ... it helps even out temps somewhat. I added the ARP unit years ago. It makes the outside fans come on sooner and stay on longer.
Yes, Iíve had one in there for a while, and the temperature that the fridge is displaying is right on. I do have a fan in there.

What bugs us the most is the intermittent nature of this problem. It will be fine for several days, then for no reason at all, the temperature starts to climb. Last night it started well after the fridge had been opened at all.
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Old 01-12-2020, 12:10 PM   #11
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What's the ARP you used?
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Old 01-12-2020, 01:18 PM   #12
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Quote:
Originally Posted by boisesmith View Post
What's the ARP you used?
What is ARP?
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Old 01-12-2020, 03:57 PM   #13
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https://www.arprv.com/dometic-rm1350.php

This is the ARP Fridge defend for Dometic 1350. Personally I donít see the need
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Old 01-12-2020, 08:21 PM   #14
rohrmann
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This is from the Dometic 1350 fridge owners manual:


The refrigerator has been design with an automatic cooling
unit cycling system that helps reduce frost build up in the fresh
food compartment. The first automatic frost reduction cooling
unit cycle begins 60 hours after turning "on" the refrigerator
(for best operational results the refrigerator should be turned on
anytime between 4 and 10 PM), and will last for approximately
120 minutes. Thereafter, the cycle will automatically repeat
every 48 hours as long as the refrigerator continues to run.


We have a Norcold, which also has a defrost cycle system, and we see a temperature fluctuation as well and is usually from the defrost cycle. We also have the ARP device, and it has kept our unit working well, especially after not having the ARP device and having the cooling unit fail twice in one year. Our fridge is usually about 34 to 40 degrees and the freezer section runs from 10 to 20 degrees. Along with the ARP device, we also have the ARP fans that the device controls independent from the factory fans, and this really makes a huge difference in how the fridge operates.
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Old 01-13-2020, 11:45 AM   #15
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Quote:
Originally Posted by rohrmann View Post
This is from the Dometic 1350 fridge owners manual:


The refrigerator has been design with an automatic cooling
unit cycling system that helps reduce frost build up in the fresh
food compartment. The first automatic frost reduction cooling
unit cycle begins 60 hours after turning "on" the refrigerator
(for best operational results the refrigerator should be turned on
anytime between 4 and 10 PM), and will last for approximately
120 minutes. Thereafter, the cycle will automatically repeat
every 48 hours as long as the refrigerator continues to run.


We have a Norcold, which also has a defrost cycle system, and we see a temperature fluctuation as well and is usually from the defrost cycle. We also have the ARP device, and it has kept our unit working well, especially after not having the ARP device and having the cooling unit fail twice in one year. Our fridge is usually about 34 to 40 degrees and the freezer section runs from 10 to 20 degrees. Along with the ARP device, we also have the ARP fans that the device controls independent from the factory fans, and this really makes a huge difference in how the fridge operates.

Thanks. DH is looking into this stuff.
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Old 01-13-2020, 11:56 AM   #16
ChuckS
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Before I’d put money into an add on kit for the fridge I’d do a complete and thorough check of the door seals verify8ng they are tight when closed.

A dollar bill works best. If the doors are nit closed properly due to adjustment your fridge will work itself to death.

I’d also take a few minutes and test the thermistor and verify it is functioning within design ohm readings. This is an easy test

Then verify the condenser coils are clean and baffle plate is positioned properly outside at upper vent.

My RM1350 is 7 years old and has always worked well on 120 or propane. 34 to 36 temp indicated on the door readout in 100 degree weather.

YMMV
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Old 01-13-2020, 08:09 PM   #17
Loneoak
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Quote:
Originally Posted by ChuckS View Post
Before Iíd put money into an add on kit for the fridge Iíd do a complete and thorough check of the door seals verify8ng they are tight when closed.

A dollar bill works best. If the doors are nit closed properly due to adjustment your fridge will work itself to death.

Iíd also take a few minutes and test the thermistor and verify it is functioning within design ohm readings. This is an easy test

Then verify the condenser coils are clean and baffle plate is positioned properly outside at upper vent.

My RM1350 is 7 years old and has always worked well on 120 or propane. 34 to 36 temp indicated on the door readout in 100 degree weather.

YMMV
Interesting information. We did a light test before we went south. We put a flashlight in the fridge and turned out all the lights. No light escaped from the fridge. Besides, if it were the seals, then wouldnít the temperature be high all the time, not some of the time?

Most of the time, the fridge works very well. It just occasionally goes haywire. Thatís when it worries us.
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Old 01-14-2020, 05:36 AM   #18
ChuckS
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You will get a much more accurate test of the seals by using a dollar bill. Each time the doors are opened and closed if the center flap on the 1350 doesnít position itself properly the seals will not seal...
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Old 01-14-2020, 12:34 PM   #19
Loneoak
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Quote:
Originally Posted by ChuckS View Post
You will get a much more accurate test of the seals by using a dollar bill. Each time the doors are opened and closed if the center flap on the 1350 doesnít position itself properly the seals will not seal...

If the seals were the problem, then wouldn't it be a problem all the time, not intermittently?


By the way, Iv'e been keeping track, and the temperature is fine for three days, then it starts to go up again. It happened on Wednesday, Saturday, and it's doing it now. It's on some kind of a three day cycle.
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Old 01-15-2020, 04:37 PM   #20
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Lots of good advice here but I’d like to add what we did. I purchased a small fan for internal use inside the fridge .
it runs on a couple of AAA batteries. This fan has really worked well for me and doesn’t take up much space. Just a suggestion.
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