Dometic Fridge issues; advice needed

Hilldweller

Super Active Member
Mar 2, 2021
1,057
Hog Waller, GA
Glad you chimed in, Bill. I just used the multimeter to check the battery. It read 12.92 volts, so I think it's good. That's usually what it reads (or lower) in the mornings when we're using the solar kit. So it seems like my removing the cut off fuse is where things went wrong. Given that none of the lights work (the easiest to check whether my battery is working is the orange exterior light just above the tongue), it seems like no power is getting beyond the cut off fuse, which is right at the battery. I'm left to wonder whether debris got into the housing when I pulled it out (unlikely) or WTH is going on. I'm such a novice with electricity, sigh.
12.92 is a great resting voltage considering the parasitic drain from the gizmos. Hopefully you're not reading that with the Shore Power or solar connected though, right?
Like @Firehawk068 said, start looking for blown fuses and/or fried wires. You can also look for shorts to ground by unhooking your battery, unplugging Shore Power, put your red probe on the hot wire and black on a ground. You're checking for continuity here so set your meter thusly and listen for the tone. If you have tone you'll need to find where/which wire is still shorted. Do that by determining which direction it goes in (ohms) and chase it down. You don't have very long runs there so it shouldn't be too hard.
 

Campeador

Active Member
May 22, 2021
142
Fort Worth, TX
Thanks for this concise summary. It seems that the positive wire broke free in transit then. I'll look over the fuses in the converter.
Update: I now have DC power to my camper. Circuit #6 had a bad fuse, so I replaced it. All lights and the converter fan work now. Thanks! Unfortunately, the fridge still doesn't turn on, so I'm back to the drawing board there. I'll check the power at the DC terminal block and check the thermal fuse. Unfortunately, that isn't listed in the diagram in my manual. I'm guessing it's the 30 amp fuse visible in the lower access / rearview equipment.
 

Campeador

Active Member
May 22, 2021
142
Fort Worth, TX
12.92 is a great resting voltage considering the parasitic drain from the gizmos. Hopefully you're not reading that with the Shore Power or solar connected though, right?
Like @Firehawk068 said, start looking for blown fuses and/or fried wires. You can also look for shorts to ground by unhooking your battery, unplugging Shore Power, put your red probe on the hot wire and black on a ground. You're checking for continuity here so set your meter thusly and listen for the tone. If you have tone you'll need to find where/which wire is still shorted. Do that by determining which direction it goes in (ohms) and chase it down. You don't have very long runs there so it shouldn't be too hard.
I'm ignorant about electricity, Bill, but not THAT dumb! LOL. It was 12.92 because I had it plugged in all night. I unplugged it before checking, of course. Thanks for your help, as always.
 

Hilldweller

Super Active Member
Mar 2, 2021
1,057
Hog Waller, GA
I'm ignorant about electricity, Bill, but not THAT dumb! LOL. It was 12.92 because I had it plugged in all night. I unplugged it before checking, of course. Thanks for your help, as always.
After you unplug it check the voltage at intervals. Batteries will display a splendid surface charge that will drop like a led zeppelin if the battery is buggered. I usually wait at least an hour before my first reading. Then an hour later with no load on it.
 

Hilldweller

Super Active Member
Mar 2, 2021
1,057
Hog Waller, GA
Update: I now have DC power to my camper. Circuit #6 had a bad fuse, so I replaced it. All lights and the converter fan work now. Thanks! Unfortunately, the fridge still doesn't turn on, so I'm back to the drawing board there. I'll check the power at the DC terminal block and check the thermal fuse. Unfortunately, that isn't listed in the diagram in my manual. I'm guessing it's the 30 amp fuse visible in the lower access / rearview equipment.
Do the short to ground testing I described. If you shorted the board, the short is probably still there.
 

Campeador

Active Member
May 22, 2021
142
Fort Worth, TX
A thermal fuse does not look like a normal auto fuse. It might be incased in some plastic.
Is it either the 3 amp or 5 amp fuse inside the power module (black case)? They are both small glass fuses instead of the plastic fuses with the numbers on them. I replaced the 3a because it looked fried, but that didn't do it. I also checked the 30 amp fuse (perhaps thats the safety fuse?) and it looked good.

@Hilldweller I'll try the short to ground testing you mention. Hopefully I can figure out how to do that! I'm learning how to use this multimeter. Fun stuff, but electricity scares me. Wish I'd worked with my uncle John, the electrician, as a teen instead of my dad, who was an HVAC / pipe insulator. My humanities PhD isn't terribly useful here, (what would Plato do?) ... except for the love of learning, I guess.
 

Hilldweller

Super Active Member
Mar 2, 2021
1,057
Hog Waller, GA
Is it either the 3 amp or 5 amp fuse inside the power module (black case)? They are both small glass fuses instead of the plastic fuses with the numbers on them. I replaced the 3a because it looked fried, but that didn't do it. I also checked the 30 amp fuse (perhaps thats the safety fuse?) and it looked good.

...
The glass fuses are "fast blow" fuses ---- see if you can find another one in line somewhere and that might be the culprit.
If your other fast blow fuse keeps going you probably have a short still.
Finding a short --- try to determine which direction it's going in by disconnecting somewhere and checking for ground in two different directions.

Edit: in your picture I'm seeing a bluish thing to the left of the little black box on the circuit board. I'm thinking there's a 5a time delay fuse in there. Check that puppy.
 
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Johneliot

Active Member
Silver Supporting Member
Jan 1, 2022
255
Chico, CA
This is a picture of a dometic fridge in a Lance trailer, but it should give you an idea. The fuse is in that black plastic thing behind the stack.
 

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Johneliot

Active Member
Silver Supporting Member
Jan 1, 2022
255
Chico, CA
The thermal fuse is to shut down the system if its not cooling correctly so it doesn’t start a fire. That’s why it’s connected to that exhaust stack. I’m not sure if when it shuts down it’s everything, even the panel.
 

Campeador

Active Member
May 22, 2021
142
Fort Worth, TX
The glass fuses are "fast blow" fuses ---- see if you can find another one in line somewhere and that might be the culprit.
If your other fast blow fuse keeps going you probably have a short still.
Finding a short --- try to determine which direction it's going in by disconnecting somewhere and checking for ground in two different directions.

Edit: in your picture I'm seeing a bluish thing to the left of the little black box on the circuit board. I'm thinking there's a 5a time delay fuse in there. Check that puppy.

Checked that 5a time delay fuse and it looked different from the new ones in that it had two little metallic balls on the fiber/ line that runs through the fuse. I replaced it, hopeful that it would be the culprit. Still, nothing. Sigh. All the other fuses at the converter are in good shape. I'm not exactly clear on how to conduct the continuity test you mention. Would you do this at the wires, lifting the bed to get behind the converter? My greeness is really showing now! Starting to think it's time to look for an RV mechanic. I also continue to have issues with the commode, so hopefully they can resolve both issues.

Edit to add: Bill, do you know whether our fridge even HAS a thermal fuse, and if so, where in heck it is? I only see the 30 amp fuse (which I suspect is the safety fuse) and the 3amp and 5 amp glass fuses inside the black box. Dometic associate on the phone mentioned thermal fuse, and thermal disc, neither of which are listed in the appendix diagrams.
 

Hilldweller

Super Active Member
Mar 2, 2021
1,057
Hog Waller, GA
Checked that 5a time delay fuse and it looked different from the new ones in that it had two little metallic balls on the fiber/ line that runs through the fuse. I replaced it, hopeful that it would be the culprit. Still, nothing. Sigh. All the other fuses at the converter are in good shape. I'm not exactly clear on how to conduct the continuity test you mention. Would you do this at the wires, lifting the bed to get behind the converter? My greeness is really showing now! Starting to think it's time to look for an RV mechanic. I also continue to have issues with the commode, so hopefully they can resolve both issues.

Edit to add: Bill, do you know whether our fridge even HAS a thermal fuse, and if so, where in heck it is? I only see the 30 amp fuse (which I suspect is the safety fuse) and the 3amp and 5 amp glass fuses inside the black box. Dometic associate on the phone mentioned thermal fuse, and thermal disc, neither of which are listed in the appendix diagrams.
Continuity test ---- everywhere along the circuit. With the trailer unplugged and battery disconnected. Touch your probes together first so you know the sound of a short, then touch the whites to blacks anywhere you find them exposed. If it rings, time to find the short by disconnecting the circuit everywhere and checking in different directions.

Thermal fuse. They all look different and I have no idea what ours would look like. Google it for images and you'll likely get a few pages worth to compare.

Good luck with scheduling service. Shops around here have several months wait.
 
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S4nsc

Active Member
Jan 30, 2021
116
St Augustine, FL
Do you have voltage at the terminal block where the wire came disconnected previously? With you meter measure voltage across the two wires. If you have voltage there the problem is at the fridge, if you don’t have voltage there the problem is between the fridge and your converter.
 

S4nsc

Active Member
Jan 30, 2021
116
St Augustine, FL
Current (amps) is like water. It will flow and take the path of least resistance.

Voltage (volts) is the potential difference between a point and a reference (ground in this case) that causes the current to flow. Voltage does NOT flow.
 

Campeador

Active Member
May 22, 2021
142
Fort Worth, TX
Do you have voltage at the terminal block where the wire came disconnected previously? With you meter measure voltage across the two wires. If you have voltage there the problem is at the fridge, if you don’t have voltage there the problem is between the fridge and your converter.

Yes, thanks for reminding me. I meant to include that info. I have 12.84 at the DC wire where it enters the fridge. I was thinking along the same lines as you. I think I'll unscrew the panel where the on switch is at the fridge (and the cooling settings, etc.) and measure there. I'm guessing I won't have any voltage there.
 

S4nsc

Active Member
Jan 30, 2021
116
St Augustine, FL
Yes, thanks for reminding me. I meant to include that info. I have 12.84 at the DC wire where it enters the fridge. I was thinking along the same lines as you. I think I'll unscrew the panel where the on switch is at the fridge (and the cooling settings, etc.) and measure there. I'm guessing I won't have any voltage there.

Check the plugs on the control boards. Probably not much else to check beyond that. Might have cooked something on one of the boards when it arced to ground.
 




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