Dometic RM7030 (Royale Series)

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sivartb000

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Jun 26, 2019
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I have a 1995 5th wheel with a Dometic RM7030 refrigerator. When I turn it on using propane it starts right up, will run for a minute or two, and then turn off. I have to turn it back on multiple times (about 10 minutes worth of cycling), and then it will finally stay on. Once on - it seems to be good. It ran for 2 full days without turning off again (until I towed it today). However, in order for it to do that, I have to have it on the coldest setting so that it literally never turns off (which is fine during the 90*+ days, because that keeps it right in the refig safe zone) - but at night that drops it down to about 20* in the fridge. Problem is, if I turn it down at night - once it kicks off, it wont turn back on (or atleast it wont stay on).

I am thinking thermocouple. In the manual, it says to test the thermocouple  if it will stay on for 30 seconds, then the thermocouple is good. Using that test - it definitely stays on for over 30 seconds. But, I'm not totally convinced that that rules it out.

Thoughts? Any other things to check? I did half-ass clean the thermocouple, so after I tow it again this evening I will do a more thorough cleaning. Trying to brainstorm my next step if a thorough cleaning doesn't fix the issue.
 

Henry J Fate

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Sounds like the ignitor/flame sensor has failed. The device does 2 things. It will ignite the gas then verify that the flame is burning.

It sounds like it is igniting fine but not confirming that the flame is burning. This will result in a shutdown

Local rv dealer will have a replacement. Installation is fairly easy.
 

sivartb000

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Jun 26, 2019
Posts
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Henry J Fate said:
Sounds like the ignitor/flame sensor has failed. The device does 2 things. It will ignite the gas then verify that the flame is burning.

It sounds like it is igniting fine but not confirming that the flame is burning. This will result in a shutdown

Local rv dealer will have a replacement. Installation is fairly easy.

This fridge has a burner tube with an electrode ("sparker" as I call it, same general theory as a gas BBQ) to ignite, and then the thermocouple is the flame sensor. So yes - same concept that I am thinking - its just not sensing the flame until the themocouple gets up to a temperature higher than it should need to be or at least thats my theory.
 

Henry J Fate

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Yup. Replace the thermocouple. Shouldn't be more than $20 at the RV shops. Cheaper online but I assume you would want to get now and install.
 

sivartb000

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Jun 26, 2019
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Henry J Fate said:
Yup. Replace the thermocouple. Shouldn't be more than $20 at the RV shops. Cheaper online but I assume you would want to get now and install.

Thanks. I'm on the same page. Thinking more about it, I did replace the Re-Igniter a few months back because I wasn't receiving any spark - that fixed the spark issue. Not positive, but I think the thermocouple is also controlled by that same box, or at least "interprets the data" so to speak? Anyways, if thats the case, it should be good since its basically new - but maybe it has failed already, or I need to double check my connections.
 

Henry J Fate

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I believe the spark and thermocouple are a single assembly performing both flame ignition and verification. Here is a manual that should be helpful

https://www.google.com/url?sa=t&source=web&rct=j&url=http://rvrefrigeratorrepair.com/wp-content/uploads/2016/07/Dometic-Service-RM7030.pdf&ved=2ahUKEwi5ut78wYfjAhVEJt8KHVY8BboQFjAAegQIBxAC&usg=AOvVaw0kDRyvgcSYHhADI7m2UljQ
 

Alfa38User

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Make sure that "sparker" is sitting properly in the flame. Also check the wire connection at the board end, they often get corroded and will not send a reliable signal to the detector board. (As Henry J mentioned, the 'sparker' and detector unit are the same physical unit, it does both jobs).
 

8Muddypaws

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It could be that the flame is weak and thus doesn?t generate quite enough heat to trigger the flame sensor.  Open up the flame inspection port and using a small brush or even compressed air remove any rust or crud that may have come down the flue from the burner assembly.

The other cause of this could be spider web in the gas tube.  It takes surprisingly little obstruction to disrupt the flow.  Spiders in particular seem to like the smell of propane.
 

sivartb000

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Jun 26, 2019
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Alfa38User said:
Make sure that "sparker" is sitting properly in the flame. Also check the wire connection at the board end, they often get corroded and will not send a reliable signal to the detector board. (As Henry J mentioned, the 'sparker' and detector unit are the same physical unit, it does both jobs).

I attached a diagram of how this fridge is set up. It has a "sparker" to start the flame, and then the thermocoupler senses the flame (just like your home water heater monitors the pilot). It sounds like its common to have a "sparker and sensor" in one combo - but I dont believe that to be true in my case. Either way, the concept is the same. I will definitely check the wire connections, but it seems to me that if it were a connection issue, it should go out at anytime, whereas in my case it seems to be OK once it gets hot enough.

8Muddypaws said:
It could be that the flame is weak and thus doesn?t generate quite enough heat to trigger the flame sensor.  Open up the flame inspection port and using a small brush or even compressed air remove any rust or crud that may have come down the flue from the burner assembly.

The other cause of this could be spider web in the gas tube.  It takes surprisingly little obstruction to disrupt the flow.  Spiders in particular seem to like the smell of propane.

Im going to clean the tip of the sensor better, but everything else looks really clean - no rust etc. The flame "seems" good - but I dont really know what it "should" look like. If a new thermocoupler doesn't fix the issue, I can try taking it off and cleaning it out.

We're heading out today for 5 days, so I'm frantically trying to come up with a number of solutions. Obviously something is wrong, and I just hope it doesn't go completely dead before we get back!
 

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8Muddypaws

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Try following the thermocouple wires back to the control board.  Take the connectors off and on a few times.  At the low voltages found in that circuit it doesn?t take much corrosion to mess things up.
 

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