Dometic RM2862 Issue

DRMartin · April 9, 2020

Just bought a used 5th wheel with the Dometic RM2862 fridge. The lights were not working so i reset the heat stack circuit fuse and they came on. Then it would only run on gas and still not cool. I replaced the 5 amp 120v fuse as it was blown and it showed to be on AC but not cooling and eventually blew that fuse again and all lights are out again.... Any ideas? I greatly appreciate any help.

Dutch_12078 · April 9, 2020

That suggests a partially shorted heater element to me.

Kirk W · April 9, 2020

All of the lights out would make me believe that you have lost both 12V and 120V power, since all of the controls operate on 12V. There are two fuses, a 3A that supplies 12V and the 5A supplies power to the electric heater, only. I suggest that you start by downloading the service manual available from this internet manual link. Do you have a reasonably quality volt/ohm meter? You really need a meter to do any significant troubleshooting. Dutch could be right about the heater being shorted but you really need an ohm meter to check that and it would also help to determine if your refrigerator is being supplied the proper voltages and to verify a failed fuse.

tsoileau · April 16, 2020

I need to piggy back on this thread since I have a Dometic rm2862 fridge that stopped working. I have the rv parked for a while and took it out to clean and get it ready for camping. Nothing comes on the fridge. I checked the power in the rear of the fridge and there is 120v and 12v on the block. I downloaded the manual for this unit and one of the things is says to check is the DC voltage at the plug1. It states that thermal 4, the orange wire is + and terminal 5, the red wire is -. When I look at plug 1 on the board, thermal 4 wire is brown and terminal 5 is black. Did check those terminals anyway and no voltage. Any advice is appreciated. PS. Did check the three fuses-two on the board and another separate from those and all are good. Thanks

Kirk W · April 17, 2020

12 hours ago, tsoileau said:

I checked the power in the rear of the fridge and there is 120v and 12v on the block.

Welcome to the Escapee forums! It seems the person who started this thread has not been back in several days, but we will do our best to help you. Since you did find power on the terminal block, am I correct to assume that you mean the in the rear of the refrigerator where power enters the harness of the refrigerator?

Quote

Check for DC voltage at Plug 1, Terminal 4 (orange wire) and terminal 5 (red wire) negative (-) DC on the lower circuit board. If no voltage, then check fuse condition. Check for DC voltage between J4 and J10 terminals on the lower circuit board.

Is this the instruction that you are reading in the service manual? What color are the two wires where you did find 12V power? Physically trace those wires to the plug on the refrigerator circuit board and verify power there and what pins of the plug they connect to and verify that 12V is there. All control functions and all lights of your refrigerator are supplied by 12V so don't be concerned about 120V power until you resolve this issue. For safety reasons, I suggest that you pull the plug for 120V.

D&J · April 17, 2020

On 4/9/2020 at 12:54 PM, DRMartin said:

Just bought a used 5th wheel with the Dometic RM2862 fridge. The lights were not working so i reset the heat stack circuit fuse and they came on. Then it would only run on gas and still not cool. I replaced the 5 amp 120v fuse as it was blown and it showed to be on AC but not cooling and eventually blew that fuse again and all lights are out again.... Any ideas? I greatly appreciate any help.

I read your post again and you state that even on gas it doesn't cool and the stack fuse was tripped. The stack thermal fuse trips with high heat exchanger temps to stop fires not over current. I'm thinking your cooling unit is bad, probably a plugged heat exchanger.

Denny

tsoileau · April 17, 2020

2 hours ago, Kirk W said:

Welcome to the Escapee forums! It seems the person who started this thread has not been back in several days, but we will do our best to help you. Since you did find power on the terminal block, am I correct to assume that you mean the in the rear of the refrigerator where power enters the harness of the refrigerator?

Is this the instruction that you are reading in the service manual? What color are the two wires where you did find 12V power? Physically trace those wires to the plug on the refrigerator circuit board and verify power there and what pins of the plug they connect to and verify that 12V is there. All control functions and all lights of your refrigerator are supplied by 12V so don't be concerned about 120V power until you resolve this issue. For safety reasons, I suggest that you pull the plug for 120V.

I checked voltage at the terminal block in back of fridge and it read 13.55 volts. Checked for voltage on plug 1 and could not get any readings. The manual says to check the voltage on plug 1 from terminal 4 + (orange wire) and terminal 5 - (red wire). On my board, picture attached, terminal 4 is a blue wire and terminal 5 is black--unless I'm reading this wrong. I also went to the bottom of the circuit board and pulled the connections off of the positive connection and the ground connection--no voltage. From what I understand from the manual, if there is no voltage there, then the circuit board is bad---again I could be way off the mark. On another note, the limit switch on the condenser coils at the top of the fridge needs to be change-I touched the connection and the terminal fell off--ordered a new one. Don't know if this plays into the problem. Thanks again for your help.

Kirk W · April 17, 2020

I have worked on a 2852 but not the 2862, but suspect that they are very close. If it were me, I'd measure between the red and orange wires to see what you find there. it is possible that you have a different lower circuit board as there are more than one version.

I found another source for manuals for the refrigerator that you have which may be helpful.

tsoileau · April 18, 2020

Checked for voltage between the red and orange wire--no reading. Thanks for the extra source--looks like it has a board like the one I have. Since there is no voltage, do you think its the main board?

tsoileau · April 18, 2020

Update: Traced wiring from dc voltage block to thermofuse and there was a reset button--pressed it and power!! Now I have to wait to see if it cools which will take a while. Will update--thanks for all the help and I hope I don't have to figure out why its not cooling. Sometimes its the simplest things--didn't realize there is a reset--hope this helps someone else down the line.

Kirk W · April 18, 2020

2 hours ago, tsoileau said:

there was a reset button--pressed it and power!!

if that reset button is located on the boiler/burner area, it is probably the safety device that Dometic added in an effort to prevent an overheated boiler from causing a fire. While you are in the back of the unit, look closely for any signs of a yellow powder or mud that may indicate a loss of coolant, which would prevent the refrigerator from cooling and also cause that over temperature device to open. If that is the case, no amount of electrical parts will help, you need a new cooling unit, or possibly a new refrigerator. How old is the refrigerator? Most cooling units last for about 10 years.

tsoileau · April 27, 2020

I bypassed all the controls and connected the heating element directly to 120 in order to determine if it was a cooling problem or a control one. Ran the unit through the night and the next morning no cooling what so ever. Looks like I need a new unit. Thanks for all your help. Take care.