We run into an intermittent issue with our Dometic absorption fridge. It’s a typical propane RV one, not a residential type. For about 3-4 days the temperature goes up into the 40s and doesn’t come down. The outside temperature is usually in the 90s and, of course, in direct sun. The freezer goes to 20. We have extra fans behind it on top by the cooling fins and an extra fan running inside to move the air around.
There are remote temp monitors so we watch the temp climb in both compartments. We travel about 2 to 3 months at a time and then, after a few days, magically the fridge starts to behave again. Our thoughts are maybe a defrost timer gets stuck on and it stays in a defrost cycle for a few days? Any ideas on how to make it stop doing this? Thanks! —Dee, 2019 Rockwood Signature 5th wheel
I have a couple of questions. Is there a change in the ambient temperature when this happens? You state it’s 90 degrees and sitting in the sun, so does it go back to normal even if the temp is 90? If you have a slightly blocked cooling unit, it will work fine at 60-75 degrees but then will struggle in the hotter temperatures. Check and document the inside and outside temperature before, during and after this occurs.
What mode is this happening in? If it’s AC, have you tried switching to LP or vice versa? You want to verify it’s not a power issue such as low voltage or low propane pressure. If it does it on both modes, it’s something in the ref controls.
Low voltage at the campground might be the problem with your fridge
Are you plugged into a campground or other electrical source? If so, do you have a surge protector or other device that can verify 120-volt power? I have found that at peak times, some campgrounds will have a voltage drop especially during hot temperatures as everyone is using their air conditioners. Low voltage will not heat the rich solution well enough to create the process the absorption refrigerator is designed for. A handy device to have is a voltage meter like this one plugged into an interior outlet at all times to verify proper voltage.
Are you in the same spot when this happens? By that I mean if you are parked level and it works for several days, then gets hotter and you have not moved, it’s not an issue with the fridge being out of level in a new spot. When it goes up to 40 degrees, have you noticed if the unit is actually working?
I do not know of a defrost timer on an absorption fridge. However, there is a temperature sensor on the cooling unit that will shut the unit down when it gets hot. That is to eliminate extreme heat that could cause building materials close to the cooling unit from catching on fire.
The cooling unit typically can run 200 degrees or higher in normal operation. However, if the unit is blocked, the temperature can get to 800-900 degrees. It’s possible the cooling unit gets hot, the temperature sensor shuts it off temporarily, and then it starts again. Possibly the on-and-off condition will only allow the unit to get down to 40. Then the ambient temperature goes down, or the sun is not shining, and the temps don’t get high enough to set off the sensor.
If you are running on LP mode, then I would suggest cleaning out the burner assembly, getting the LP pressure tested, and checking your house batteries. These are all covered in the following “Gremlins” article.
You might also enjoy this from Dave
RV ‘Gremlins’, Part 3: The secrets of RV absorption refrigerators
In this edition of RV Gremlins, Dave tries to figure out the gremlins in RV absorption refrigerators.
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
Read more from Dave here.
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