Dometic Refrigerator "cycling"

Hi, I have a Dometic DM2852 model refrigerator which ran fine for 8 years. Just lately it has started "cycling". That is it won't run for more than 10 secs then stops. Then runs for 10 secs and stops. This is on 120v AC. I have not tried it on gas. It is still staying cold and freezer still okay but obviously this is not normal. Could it be low on Ammonia or Hydrogen ? Can these units be "topped up" if so. Or is it more likely to be a control issue, thermocouple etc. How can it be checked ? Thanks for any info.
 

Bogie

Well-known member
You should look at the diagnostic manual under the tools section of the Forum. Here is a direct link to the manual posted there. One of the first steps is to try running on gas to see if you have the same result.

How are you determining the 10 sec on/off cycling. Since the cooling system is virtually silent, are the lights cycling? Or....something else?
 
You should look at the diagnostic manual under the tools section of the Forum. Here is a direct link to the manual posted there. One of the first steps is to try running on gas to see if you have the same result.

How are you determining the 10 sec on/off cycling. Since the cooling system is virtually silent, are the lights cycling? Or....something else?

First off, thanks for the link. It was very informative. Also I tried it on gas and it sounds exactly the same. In fact I pulled the AC plug and the noise is still there so I believe it must be on the DC side. It sounds like a pump or compressor starting up for maybe a second and then stopping before it has chance to get up to speed. I know it is not that because there is no pump or compressor. Then about 10 seconds later it starts again Is there a fan ? I dont see one from the schematic ?
 

cookie

Administrator
Staff member
There may be a fan or two on the backside cooling fins.
Open the outside cover and take a look.

Peace
Dave
 

Bogie

Well-known member
There may be a fan or two on the backside cooling fins.
Open the outside cover and take a look.

Peace
Dave

That was my next guess. Only thing I know of that makes noise on that Fridge.

If so, the fan is controlled by a temperature sensing thermostat that is located on the top(usually), and is attached to one of the fins or coils. The thermostat and fan is meant to help drive cool air over the coils when they get hot. For me these usually only come on when it's rather warm outside or the sun is hitting the side wall of the trailer. So you may have a defective thermostat. Attached is a picture of the one on my fridge. Mine is in the kitchen slide so it vents on the side (not the roof). If yours vents on the roof, you may not have access without pulling out the fridge. Also, this picture was taken when I was modifying the fan assembly (quieter fans) which explains the large hole in the rain shield which I replaced after the mod. You can see the thermostat on the top right. BTW....factory fans are really noisy.

IMG_3474.jpg
 
Top