DOMETIC RMD8551

[1oneozzie]

G'Day 👋,

I have a Dometic RMD 8551 fridge. The control panel completely blank, and none of the buttons respond.

I have removed the control panel & there are no fuses behind that.  In the rear of the fridge, the control module is type 289 0241-20, I can't see any fuses around there, either.

Has anyone else experienced a similar problem ?, and been able to resolve it ?

Thanks ( in advance )  for any clues 👍 

 

[Pat & Pete]

There may be an in line fuse on the red power line to the control module .

There's usually a slow burn fuse under the control module cover , attached directly to the circuit board .

There's likely a fuse in the fuse panel for the rig and possibly a breaker . 

[Kirk W]

First of all, welcome to the Escapee forums! We are here to help and we will do our best. My first suggestion is that you download a copy of the Dometic service manual from Bryant RV Service website. 

The symptom that you describe is a strong indication that your refrigerator has no 12V power. With no display and no interior light that is the cause. On page 31 of the manual I linked to you will see a picture of that power circuit board and it will also point out the location of the 1a fuse for 12V power. It is to the upper left in that picture or on the circuit board. If you own volt/ohm meter it is a good idea to remove that fuse and check it with the ohm meter to be sure that it is good as you can't always tell by looking at it. A good fuse should read less than 1 ohm between the ends. If that fuse is good then use the meter to check for 12V power at the terminal block where the refrigerator connects to power. 

I am not familiar with the model of refrigerator that you have but on page 40 of the service manual it shows where the 12V and 120V connections are located and it looks like that power circuit board from the picture is the green item on the top of the refrigerator box to the left corner.

[1oneozzie]

G'Day Kirk,

Yep I've downloaded that manual already 👍

It appears that the dometic model I have is an " aussie model" & none of the PC's shown are any thing like what I find behind the panels.

I believe that the control module ( P/N 289 0240-20 ) has a fuse in it.  The model I have is fully sealed ( i.e. potted in epoxy ) & not serviceable.  On Page 26 of this manual, there is an image of the part I'm referring to. 

52181947.pdf

Edited January 30, 2022 by 1oneozzie

[Kirk W]

Good morning! Or at least it is morning here in Texas. 😊 I had not noticed your location in that first post but it does explain a few of the things I had found puzzling about the service manual. The service manual that I linked to is posted on a site by an RV service tech in Florida and while of little help, it does have a picture of the part you referenced, Burner Control Device P810 on page 35. In addition, on page 42 of the manual in my link there is a picture of a terminal block that seems to correlate to what is shown in the electrical diagram in the manual in your post on page 24, bottom of the page and labeled A,  B, C, & D. That makes it seem that there is some information in the manual in my link that applies to the one you have, even though the two are clearly configured quite differently.

I am wondering if removal of the 2 screws at the top of that Hea Tec on your diagram might possibly enable removal of the plastic cover to gain access to the circuit board? In Dometic refrigerators that we see in RVs here in the USA it is very common to have a plastic cover over the circuit board and the screws that hold the board in place are hidden under that cover.

I have also found an operating manual for what appears to be the same refrigerator that you have and it has a trouble shooting section on page 25 that replacing of a fuse but makes no mention of where it is or how to replace it.

I forgot to mention that we have a resident Aussie, Bruce T on the forum and a long time Escapee but he is up north in Gold Coast, about 1000 Km away. He might just have some experience with a model like yours.

Edited January 30, 2022 by Kirk W
add a thought

[jettel]

I'm having the same issue right now with my Dometic RMD 8555. It happens intermittently. Definitely not a fuse issue. Usually, if I wiggle the wires (12 volt) that go into the junction block on the back of the fridge it will come back on but I never know if the fridge will work for a day or a year. I have tried tightening the connections, taking them loose and checking to see they are properly seated, etc., everything seems tight and connected. I am at the point where I'm thinking either the junction block is cracked or one of the wires has an internal break that connects and disconnects with vibration? When it happens, the failure seems to happen after moving the rig. A week ago I aborted a camping trip because the fridge stopped working and my usual fix of wiggling the wires did not work. Of course at home sitting in my driveway the fridge worked fine so I tried to make it fail by wiggling one wire at a time but I could not get it to fail. Even removed the control panel and tried gently flexing it to see if it would fail. I'm stumped about how to diagnose it, any suggestions?

[1oneozzie]

G’Day jhmooney👋🏻
Im pretty sure that that mine is the internal fuse. I’ve picked up the permanent 12V feed into the control block & directly connected that to the 12V out & every-things working fine - that might be worth a try for your situation as you would be bypassing any dodgy connections.
If needs be I can post a photo, if my description doesn’t quite make sense.

Good luck 👍😎 

[jettel]

Thanks 1oneozzie, the only fuses I've found all appear to be good. However, one of the wires that I generally can wiggle to get the thing to go again is a jumper that goes from one terminal on the junction block in the back to another terminal. The wire is yellow and it has a blade type fuse holder in it. The last time it stopped working I tested both ends of the wire and was getting 12 volts at both ends of the fuse link but since it is an intermittent issue, maybe that is where the short is. I'm not aware of an internal fuse and didn't find any fuses behind the control panel. If I recall there were two in the back of the unit and one in the electrical service panel.

[Kirk W]

1 hour ago, jhmooney said:

The wire is yellow and it has a blade type fuse holder in it. The last time it stopped working I tested both ends of the wire and was getting 12 volts at both ends of the fuse link but since it is an intermittent issue, maybe that is where the short is.

I am wondering if the in-line fuse holder might be your problem? 

You can get a replacement from Amazon or any electronics store. If you were to post a picture of the terminal block you are working with, that may help us to help you. 

[jettel]

Yes there is a fuse holder like that which might be the problem. I will post a terminal block photo later today. Thanks

[jettel]

Here is a picture of the junction block. The wires I wiggle that usually get the fridge going again are the ones on the four lower right terminals (the black fuse jumper wires, yellow, orange and white).

Edited February 7, 2022 by jhmooney
provide more info.

[jettel]

Here is a picture of the components behind the fridge. I emailed Dometic and they suggested the lower control board may be bad. I can't find a controller board other than the one in the control panel on the front of the fridge. I'll have to do some research to see what they are referring to. I have an RV tech coming to look at it but I don't know if they will find anything because of the intermittent nature of the problem. Sorry for the double post, I couldn't figure out how to get two pictures in one post without exceeding the 100 kb limit.

[Pat & Pete]

Sounds like your wiggling wires is a loose or dirty connection .

Have you pulled all wires and cleaned and tightened each contact point ?

 

[Kirk W]

1 hour ago, Pat & Pete said:

Have you pulled all wires and cleaned and tightened each contact point ?

My first thought also. 

[jettel]

13 hours ago, Pat & Pete said:

Sounds like your wiggling wires is a loose or dirty connection .

Have you pulled all wires and cleaned and tightened each contact point ?

 

Yes they are tight and clean, that’s why I’m thinking one of the wires or the junction bock has a break in it. It’s the only explanation I can think of that would cause an intermittent loss of 12 volt power to the control panel.

[1oneozzie]

G'Day All,

Many thanks for all the constructive comments - it's good to see that I'm not the only one 😃

I've attached a photo of my "temporary solution" - by connecting a permanent 12v supply to the 12vout of the control module the fridge works like a charm.  As we use 240Vac in Australia, the rear of the control module is completely sealed & potted ( I'll attach a photo if ever I remove the module ).

Although I haven't had the opportunity to move the van, ( covid is all about ) The fridge has been running reliably now for over a week 👍

So I'm going to make this "fix" a little more permanent & see how we go 😎

Cheers, 🍻

[1oneozzie]

G'Day Again 👋

For all you Dometic users, there's a bloke here in Aus that makes a neat little kit to increase the efficiency of the fridge.

Its a pack of fans that go onto the external grill, senses the air temperature & switches on to increase the air flow through the system, work like a dream, particularly in warmer, high humidity locations.

Just a thought 🤔

Cheers 🍻

[Kirk W]

If that works then whatever you bypassed with the jumper wire must be the cause of your problems.

There are several refrigerator vent fan kits available here also, some powered by 12V and some 120V.

Edited February 8, 2022 by Kirk W

[1oneozzie]

11 minutes ago, Kirk W said:

If that works then whatever you bypassed with the jumper wire must be the cause of your problems.

There are several refrigerator vent fan kits available here also, some powered by 12V and some 120V.

G'Day, yep - but unfortunately the part I've bypassed is NOT accessible - made to be intrinsically safe, butnot made to be serviceable I guess ?
Cheers 🍻

[jettel]

Thanks. The wiring on your fridge looks different than mine. The only control board I have found is behind the control panel on the front so I’m still not sure where this lower control board is that Dometic is referencing. The fridge has been working perfectly in my driveway for over a week now. I sort of wish it would die permanently as I am afraid if it is working when the tech comes next week he won’t be able to diagnose the problem. So frustrating. I do have fans on the exterior vent and inside the fridge. They do seem to make it work efficiently when I’m not having the issue with power to the control panel. I usually only have set the temperature two or three bars below maximum and can make ice and keep ice cream in the freezer. Many people say they have to run them at maximum cooling to keep the freezer below 40 degrees Fahrenheit. By the way I did try to find a service manual online on a few sites including Bryant RV but none of them seem to exactly match my RMD8555. 

Edited February 9, 2022 by jhmooney
Add more info

[jettel]

Update: It turned out to be the thermal switch on the flue for the propane heating unit. One of the prongs on the switch was loose so it would make contact sometimes and sometimes not. Apparently my wiggling the wires on the junction block would cause it to make contact for awhile.

Thanks to all who responded, I appreciate the help.

[Kirk W]

Thanks for letting us know! We learn with you. 

[PeterM]

On 2/23/2022 at 9:54 AM, jhmooney said:

Update: It turned out to be the thermal switch on the flue for the propane heating unit. One of the prongs on the switch was loose so it would make contact sometimes and sometimes not. Apparently my wiggling the wires on the junction block would cause it to make contact for awhile.

Thanks to all who responded, I appreciate the help.

jhmooney, many thanks for your posting on what your issue was.

I experienced the same but with a relay that just seemed to continually open & close. It was the same issue with the contacts/prongs on the flue.

Cheers