Dometic refrigerator keeps tripping the thermal limit switch

Be glad you had the mod done... It saved your RV.

Another thing that can pop the thermal breaker/fuse is a clogged flu but I see that is not your issue. Sometimes birds nest atop it.. Kind of warm up there and a bit wind protected.. Or insects.

Glad you found your problem.. Sorry it's one you have to throw money at.

garyemunson wrote:
Over the decades I've had to replace 2 cooling units. Both were in RVs I bought used so I suspect they were not operated correctly in the past. Since I've done them myself (pretty easy as they were older, smaller fridges), it was far cheaper than replacing the entire fridge. At this point, you should take stock of how you use your RV. If you always go to RV parks wth hookups (nothing wrong with that, lots of people prefer the comforts provided!) it's time to switch to a residential type fridge. Cheaper than repairing yours even if you do all the work yourself. If you boondock at all or go to state/national campgrounds without hookups, gas fridges are still king. Switching to a residential in those cases usually involves more batteries and an inverter upgrade so you end up spending the same or more. As said above, operating out of level can make fridges run hotter outside increasing the risk of springing a leak from the repeated flexing of the steel from the greater temperature swings. You don't have to be spot on level, what happens occurs on a "sliding scale", the more out of level, the hotter the coils run. Just do your best to get the coach not too far off level and you will be OK. I've seen the obsessed using a 3' level feverishly adding/subtracting blocks to get their rig perfect. Not necessary. Also, if you live in a humid climate, leaving the RV plugged in and the fridge on electric will keep the outside coils hot and lessen chance of them rusting out at one of their welds.

https://rvcoolingunit.com/Dometic-Cooling-Units-remanufactured-C4380.aspx?sid=298

I found my unit on their website:

https://rvcoolingunit.com/DM2652-Dometic-Cooling-Unit-606a-626a-P5536108.aspx

So you think this is easy enough to replace on my own? I just emailed them to ask for installation instructions.

Also, how does this system differ from the Dometic system?

dougrainer wrote:
The Thermal fuse WORKED. That is why there is a Thermal fuse. It shut the refer down because the cooling unit overheated due to NO Ammonia and had leaked out. Doug

Yup, same thing the tech said yesterday :)

Old-Biscuit wrote:
Yellowish residue.......sodium chromate (rust inhibitor in coolant solution)

The dried residue is TOXIC
Do NOT use air compressor to blow it out

Gloves, eye protection, vacuum ----wipe down with wet cloths (dispose of them in a sealed zip lock bag)

Good to know...thanks! Will definitely not touch it and will be careful when handling it.

The Thermal fuse WORKED. That is why there is a Thermal fuse. It shut the refer down because the cooling unit overheated due to NO Ammonia and had leaked out. Doug

Over the decades I've had to replace 2 cooling units. Both were in RVs I bought used so I suspect they were not operated correctly in the past. Since I've done them myself (pretty easy as they were older, smaller fridges), it was far cheaper than replacing the entire fridge. At this point, you should take stock of how you use your RV. If you always go to RV parks wth hookups (nothing wrong with that, lots of people prefer the comforts provided!) it's time to switch to a residential type fridge. Cheaper than repairing yours even if you do all the work yourself. If you boondock at all or go to state/national campgrounds without hookups, gas fridges are still king. Switching to a residential in those cases usually involves more batteries and an inverter upgrade so you end up spending the same or more. As said above, operating out of level can make fridges run hotter outside increasing the risk of springing a leak from the repeated flexing of the steel from the greater temperature swings. You don't have to be spot on level, what happens occurs on a "sliding scale", the more out of level, the hotter the coils run. Just do your best to get the coach not too far off level and you will be OK. I've seen the obsessed using a 3' level feverishly adding/subtracting blocks to get their rig perfect. Not necessary. Also, if you live in a humid climate, leaving the RV plugged in and the fridge on electric will keep the outside coils hot and lessen chance of them rusting out at one of their welds.

https://rvcoolingunit.com/Dometic-Cooling-Units-remanufactured-C4380.aspx?sid=298

Yellowish residue.......sodium chromate (rust inhibitor in coolant solution)

The dried residue is TOXIC
Do NOT use air compressor to blow it out

Gloves, eye protection, vacuum ----wipe down with wet cloths (dispose of them in a sealed zip lock bag)

Yep, that's the end of that cooling unit. The yellow color is from chromemate which is in the solution along with ammonia inside the refrigerator. The boiler has failed. Perhaps from constant overheating from operation with the RV out of level. The thermal sensor tripped because the heater was heating the boiler but that heat wasn't being carried away as would happen if it was working normally.

The cooling unit can be replaced without replacing the whole refrigerator but the difference in cost isn't all that great and you'll only save money if you do it yourself because of the extra labor of taking the refrigerator apart and putting it back together again as opposed to pulling the old refrigerator out putting an new one back in.

I think I have discovered the issue. Spoke with a local RV repairman and he asked if there was any yellow / green fluid that had leaked behind the refrigerator. Sure enough, it can be seen here:

https://www.dropbox.com/s/7q1msqr9j5acr4s/2019-06-03_19-33-53.png?dl=0

He informed me that the refrigerator is shot at this point and will be have to be fully replaced as the coolant has leaked out. Bummer :(

I'll post a response to some of the questions earlier in a moment.

I haven't looked at a Dometic in years. Not sure what you mean by thermal limit switch. My Norcolds don't have one that I know of. I've heard other talk about an aftermarket limit device, not sure how it works.

You didn't put your model number in the post. These guys need that to give you more specific info.

The 5 amp is probably for the AC electric heating element. 3 amp for the controller board. Both fuses being blown is a bit confusing.

If your controller board isn't getting power you can't run on gas either.

When you replaced the fuses, did they blow again?

You need to measure the resistance of the heating element. They vary depending on the model. All of mine were around 300 watts. Which would be about 50 ohms.
That would make normal operation around 2.5A. If your blowing the 5A fuse yours would be around 25 ohms or less.