Dometic rm1350 - auto mode

LAURAKT · 01-19-2018, 06:46 PM

I've searched the forums for this particular question but haven't been able to find an answer: Our Dometic RM1350 refrigerator is all of a sudden flashing between LP and the temp, and it's not staying cold. Troubleshooting shows that this most likely means that there's a problem with the LP gas, like it's empty or the ignition failed. BUT, we've been using it in AC mode, not LP. According to the service manual, it should go into "Auto mode and AC operation", but it will only go into "Auto" or "LP" mode. Either option keeps the LP button on. So here's my question: Will this model just go into AUTO or AC mode, or does it have to have LP to work? In other words, should it continue to work even if our propane tanks are empty or turned off? We have been using only AC power for months - no LP at all, so we're trying to figure out why all of a sudden it is flashing between LP and the temp. We're filling a tank and seeing if that solves the problem, but shouldn't it work just on AC power? Thanks for any insight!

**ependydad** · 01-19-2018, 07:05 PM

"but shouldn't it work just on AC power" - yes it should.

5picker · 01-19-2018, 10:34 PM

Sounds like it may have lost A.C. voltage and tried to light on L.P. and couldn't. (Maybe you have tanks shut off)

Have you checked if the refrigerator outlet has current? Did you check the breaker? Have you checked the fuse(s) on the control board?

LAURAKT · 01-20-2018, 05:03 PM

So we filled the propane tanks and the refrigerator is working like it should again, but of course the LP light is on, and according to the manual, it should go into AC mode without the LP mode on.

When you say "have you checked if the refrigerator outlet has current?" and the fuses, etc., doesn't it indicate that we have current if the light inside the frig lights up (which it does)? Breakers are on, no fuses indicate any outage.

I'm not sure we have a malfunction at this point, because it's working, but all indications from manual and advice from this forum are that it should work just in AC mode even if the propane tanks are off and it doesn't, so ????

Thanks again!

**ependydad** · 01-20-2018, 05:08 PM

Can you go to the backside of the fridge and unplug it... in its place, plug in a light and see if it works?

Steve-W · 01-20-2018, 05:25 PM

The contol electronics including the interior light operate off of 12 vdc. Only the ice maker and electric element for the cooling unit operate from 120vac.
If the ice maker is working you most likely have 120vac to the unit. If thats the case you have a failure with the heating element or controler for the fridge. There is a fuse on the controller specifically for the heating element.
If the ice maker is not working then you may not have 120vac to the outlet where the fridge and ice maker plug in. The fridge and ice maker have seperate 120vac power cords, make sure both are completly plugged in.

bubbles · 01-20-2018, 07:38 PM

The only selections are AUTO and LP. AC power has priority in AUTO. If AUTO is selected and AC fails or is removed it will switch to LP and if LP fails it will flash alternately with TEMP. If AC again becomes available while LP is flashing the fridge will operate on AC but LP flashing will not cease till fridge is turned OFF and back on (power reset). Sounds like AC power was lost and may still be lost. The flashing occurred due to a lockout because of not operating when switched to LP. The modes for the fridge are selected to either AUTO or LP.

LAURAKT · 01-20-2018, 08:46 PM

We did go to the backside of the frig and unplug it, then plugged in a lamp. The lamp worked. As soon as he unplugged the frig, my husband heard the LP pilot igniter come on, so it appears to be working correctly in that way.

He's checking the fuse in the back of the frig, but it's hard to access. It still seems to be working on LP whether or not we choose AUTO. No matter what, the LP light stays lit. It's no longer flashing between LP and the temp. I think the only way we will know for sure if it is working only on AC is to go turn the propane tanks off and see if it keeps going.

(We don't have the icemaker.)

Thanks for all your help - really appreciated.

Steve-W · 01-20-2018, 09:24 PM

Sounds like there may be an issue with the heating element or controller. If you have a voltmeter, you can ckecked for ac to element and also the resistance across the element. I have a pdf file of the service manual which has most of the info you would need to troubleshoot the fridge. If you whish I will be happy to pass a copy along, just pm me your email addy and I will pass it on to you.

5picker · 01-21-2018, 08:13 AM

I'll ask again to check the glass AC fuse on the control board. Be sure to check it with a multimeter. I had one go bad on my 1350. It got hot and melted the solder internally where the fuse wire attaches. It looked good but wasn't. It got hot because the tabs that hold the fuse were spread apart too far.
I replaced the fuse and realigned the tabs and no more problems.

Turning off the propane tanks will only make the flame go out and not really diagnose your issues. You need to do some electrical testing.

Murbella7 · 01-21-2018, 04:50 PM

Quote:

Originally Posted by LAURAKT

I've searched the forums for this particular question but haven't been able to find an answer: Our Dometic RM1350 refrigerator is all of a sudden flashing between LP and the temp, and it's not staying cold. Troubleshooting shows that this most likely means that there's a problem with the LP gas, like it's empty or the ignition failed. BUT, we've been using it in AC mode, not LP. According to the service manual, it should go into "Auto mode and AC operation", but it will only go into "Auto" or "LP" mode. Either option keeps the LP button on. So here's my question: Will this model just go into AUTO or AC mode, or does it have to have LP to work? In other words, should it continue to work even if our propane tanks are empty or turned off? We have been using only AC power for months - no LP at all, so we're trying to figure out why all of a sudden it is flashing between LP and the temp. We're filling a tank and seeing if that solves the problem, but shouldn't it work just on AC power? Thanks for any insight!

I don't know the model but mine is a 3-way. When it loses AC it tries to go LP gas first then 12v. Remember that these things need a continuous 12v supply to run the control panel, regardless of the supply that operates the fridge. This is so that if it loses one of the main supply options (AC or LP or 12v) it will cycle through the other options till it finds a supply. If the LP gas is turned off and the battery volts are down to a point that they cannot supply enough power to run the fridge, (but still enough volts to run the panel), the panel will give you a song-n-dance until one if the supply options is restored. Check your circuit breakers and your battery volts.

Also, the Dometic fridges are additionally controlled by a connection (accessed via the panel on the back outside the van) called D+. This is the 'alternator' sensor connection to the tow vehicle. When you are hooked up with the tug motor running, the fridge assumes you are on the road, disconnected from the AC and with the LP turned off, (as safety and some state laws demands), so it goes into 'float' mode keeping things cool while you are driving to your next camp. When you stop and turn off the engine, the D+ line loses power and the fridge then goes looking for a knew supply source. It can do this because it still has 12v from the house battery.

At this time, unless you are Speedy Gonzales (remember him) the AC will not be plugged in and the LP is probably yet to be turned on. So, Dometic, in their infinite wisdom, built in a delay (the manual says 15 minutes), that allows you to do those things before the fridge starts cycling through its options before selecting a source.

As I said, if the LP is off, the AC is out (of action) and the 12v supply is low, then the fridge will begin its Christmas Special light show or 'having a heart attack' jig.

The D+ line sometimes fails, usually due to wires being ripped out when a tire explodes and wraps rubber around everything under the van and rips it all out and the repairer doesn't know what the wire is or forgets to reconnect it, or some other reason. If this happens then the fridge has no way of knowing if there is a 12v supply from the tug alternator when you are in motion and will not operate. Result, warm beer, and milk. So that is something else to check, if it is appropriate.

How do I know all these things...? Been there, done that.

Hope this helps.

MCCOY1998CARDINAL · 01-21-2018, 11:51 PM

Very helpful as I'm working on the fridge as we speak...I'm looking at my wiring schematic and breakdown and parts list for the cooling part of the fridge. I'm not seeing the term " D+ " anywhere. Is that a generic term for the actual sensor you refer to ? I am in process of troubleshooting and found your input very worthy to check out.
So far, Ive found considerable Mud Dauber Wasp homes built anywhere imaginable...
I have not begun testing, electrically yet. Any short help would be appreciated very much.
To think I just finished rebuilding my Suburban furnace....before the cold snap.
This is a FR Cardinal , 1998, 5th. The fridge is a Dometic RM2652...btw.

Scrapper · 01-22-2018, 01:28 AM

LAURAKT, There are Dometic RM1350 manuals in the Library section. In the light green bar at the top of this page. I believe if you are using the smartphone app you will not see the Library section.

Users Manual: Forest River Forums - Downloads - Dometic RM 1350 fridge users manual
Service Manual: Forest River Forums - Downloads - Dometic RM + RME1350 fridge SERVICE MANUAL

MCCOY1998CARDINAL: the Dometic RM2652 manuals are located in the same section.

Users Manual: Forest River Forums - Downloads - Fridge - Dometic User Guide (DM2652)
Installation Manual: Forest River Forums - Downloads - Fridge - Dometic Installation (DM2652)
Schematics: Forest River Forums - Downloads - Fridge - Dometic Schematics (DM2652)

Murbella7 · 01-22-2018, 06:20 AM

Quote:

Originally Posted by MCCOY1998CARDINAL

Very helpful as I'm working on the fridge as we speak...I'm looking at my wiring schematic and breakdown and parts list for the cooling part of the fridge. I'm not seeing the term " D+ " anywhere. Is that a generic term for the actual sensor you refer to ? I am in process of troubleshooting and found your input very worthy to check out.
So far, Ive found considerable Mud Dauber Wasp homes built anywhere imaginable...
I have not begun testing, electrically yet. Any short help would be appreciated very much.
To think I just finished rebuilding my Suburban furnace....before the cold snap.
This is a FR Cardinal , 1998, 5th. The fridge is a Dometic RM2652...btw.

With local (USA) versions of the fridge it may be called something else. It is the 12v sensor wire that should be wired back to your trailer plug, which has a pin dedicated to a 12v supply from the truck electric circuit controlled through the ignition, like the accessory line (not from the battery). This supply point must disappear when you turn off the ignition. When this line goes dead, the fridge knows to then swap supply sources.

All this is of course based on my experience with a 3-way Dometic fridge installed in our unit in the USA, BUT, a 240v version built for the Australian market (which is where I am). After the rewiring job done on our unit, this line disappeared so instead we now have a motion sensor switch in there instead. When we move, the fridge gets supply from the truck, when we stop it uses supply from one of the alternatives sources.

LAURAKT · 02-16-2018, 08:21 PM

I just wanted to post that the problem with our Dometic refrigerator seems to have been fixed. We followed the advice from numerous people on the forum, like un-plugging the refrigerator and plugging in a lamp to see if it worked (it did), and other suggestions which were much appreciated. Per 5picker's suggestion, we checked the glass AC fuse on the control board. The fuse appeared to be fine (not burnt out) so we made sure everything was clean and there was no melting or erosion and put the fuse back in and it works fine now! While before it would only go into "Auto" or "LP" mode, now it shows it is just in "Auto" mode, as it should because we are using it on AC power instead of propane power. I think the problem started initially because AC wasn't working and our propane tanks ran out so the refrigerator wasn't working at all.

It must have just had a bad connection where the fuse was plugged in and since we removed it and replaced the fuse, the connection is there now. Anyway, THANKS AGAIN everyone!

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