Domestic 1350 fridge

[Greg V]

I have a Dometic 1350 fridge in my trailer. I’ve had the rear power module fail twice on me in the last several months. First time I got an error message indicating failure. This time no error code it just stopped working on AC worked fine on gas. Replaced the glass fuse started working again for a couple of days then stopped working again. Called Dometic they indicated that it was failed power module again bad relay on the board. What would cause this to happen. 

[Wrknrvr]

 Low voltage can make amps go up and blow the fuse. Possibly be a problem for the relay also. I would think if you are sitting in one place that maybe the problem.

 

 Check voltage at post and at fridge back.

 

 Safe Travels,.   Vern

[Greg V]

Are you referring to the 120vac. I have 119 at the back of fridge 

[Kirk W]

My first thought is that if you don't have a copy of the Dometic Service Manual, you should visit the site of Bryant RV  Service and download one. 

You mention that you replaced a fuse but didn't say which fuse you replaced. The 5a fuse is in the power supply to the electric heater. The 3a fuse is the 12V supply for control so I would assume that the one you replaced was the 5a. Have you measured the resistance through the heater and between the heater lead to ground? Heatethatnrs do fail and they also sometimes collect rust from flue which can short out the element of cross it to ground, either of which can cause the 5a fuse to open. The resistace of the heating element should be around 50 to 80Ω.

[Greg V]

I replaced the 5amp glass fuse   I checked the resistance of the heater element and it is within tolerance. I have not checked the ground 

[Kirk W]

7 hours ago, Greg V said:

I have not checked the ground 

Read from each lead to the metal frame of the refridgerator. It should read very high, in the 5-10KΩ range or more. If the problem is rust it can vary with vibration of travel and be intermittant. Has the flue been cleaned recently, as rust inside of it isn't unusual? It is also possible that the fuse just failed because that too can happen but is pretty rare. Since the refrigerator worked properly on gas, you probably don't have any other problems with your lower circuit board. 

[oldjohnt]

Greg, When it fails to operate on AC is it always because the fuse has blown ???? If so, it must be drawing more then 5 amps so I would remove the connections from the board and measure element resistances as Kirk mentioned, some of which you indicate is already completed.  Sounds like the element itself line to line is okay so all that's left is line to case/frame/ground resistance. That result will tell us a lot.

That being said, if the fuse always blows which causes failure on AC operation, I lean more towards the element or it being somehow shorted then the board as the problem. However I'm not sure how and where that AC fuse comes into play on the board so sure the board may be at fault. If the element resistance is fine and there's no shorting path from the element to case/frame, then its back to a faulty board grrrrrrrrrrrrrr

Let us know

John T