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03-05-2021, 05:46 PM
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#1
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Junior Member
Join Date: Oct 2019
Location: Livingston
Posts: 25
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Dometic DM2652 - always running
I’m trying to figure out why my 2652 never stops drawing 300 watts when it runs on AC. It works great - keeps freezer frozen and refrigerator ~34F. It does not have the Climate Control function, so that’s not the issue. I tested the thermistor - get 8980 ohms when it’s in ice water which is within spec.
Is there anything I should test (I’ve got a multimeter) before I just buy a new circuit board for $100 and hope that fixes things?
Any help is appreciated!
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03-05-2021, 05:54 PM
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#2
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Site Team
Join Date: Jul 2014
Location: Modesto
Posts: 20,357
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Have you tested the heating element? Is it “shutting off” like the LP flame goes out?
__________________
![](image.php?s=654699a44c3f599c561397c213037f38&u=14512&type=sigpic&dateline=1418489574)
2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.
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03-05-2021, 06:00 PM
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#3
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Junior Member
Join Date: Oct 2019
Location: Livingston
Posts: 25
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I don’t know how to test the heating element.
All I know is that the unit (when on AC current setting, not using LP gas) is always pulling 300 watts. Since the refer works, I assume the heating element is always working. I think it issue is “why won’t it turn off”. And I already know it isn’t the thermistor since it tests correctly.
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03-05-2021, 06:07 PM
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#4
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Site Team
Join Date: Jul 2014
Location: Modesto
Posts: 20,357
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If you look at the board, there are 2 connections to the eating element. Use an amp clamp set to AC amps. I would test at “start up” should be about 1100W I would think. And then again after the fridge has reached temp.
__________________
![](image.php?s=654699a44c3f599c561397c213037f38&u=14512&type=sigpic&dateline=1418489574)
2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.
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03-05-2021, 06:40 PM
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#5
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Junior Member
Join Date: Oct 2019
Location: Livingston
Posts: 25
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If I can borrow an amp clamp and a second pair of hands I can try that. How would this test help me understand why the element never turns off?
I’m pretty sure that my inverter software has given me the answer already: about 330 watts at startup for a few seconds and then 305 watts continuous. Here’s a pic with all power in the rig off (except some parasitic, 3 watts) and with the fridge turned on.
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03-05-2021, 06:44 PM
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#6
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Site Team
Join Date: Jul 2014
Location: Modesto
Posts: 20,357
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My brain isn’t in gear anymore this evening, I’ll have to think about it.
__________________
![](image.php?s=654699a44c3f599c561397c213037f38&u=14512&type=sigpic&dateline=1418489574)
2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.
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03-05-2021, 07:36 PM
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#7
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Site Team
Join Date: Mar 2011
Location: Gaylord
Posts: 26,998
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The DM2652 electric heating element is a 210 watt heater. It's connected to the refrigerator control board at J7 and J8 (two black wires).
If you're trying to "eliminate the refrigerator heating element from the mix, why not simply disconnect both the black wires on the control board at J7 and J8 ??? That will effectively remove the "amp drain" of the heating element, simulating the thermistor/control board "turning it off"... The wattage reading you get at that time will tell you what the refrigerator "should be drawing when the electric heating element is turned off/removed from the circuit"
My guess is that you're still likely going to have some amperage drain, even with the heating element "removed from the circuit". Whether it will be 380 watts is something I can't tell you. It won't be "0 watts" but I'm not sure how much there will be.
NOTE: Don't disconnect only one of the two heater black wires. Doing that will allow the "full 120VAC potential (before the fuse blows) to flow from the remaining "connected connector" through the element and into "whichever fingers touch the bare contacts on the other end of that black wire... So, disconnect BOTH J7 and J8.....
__________________
John
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS
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03-06-2021, 06:21 AM
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#8
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Senior Member
Join Date: Mar 2014
Location: Mountain Home, Idaho
Posts: 3,015
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__________________
2007 GMC Classic club cab 4x4 Duramax LBZ
2014 Alpine 3010 RE. 34 foot fifth wheel
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03-06-2021, 06:29 AM
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#9
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Senior Member
Join Date: Apr 2019
Location: Henniker
Posts: 2,185
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I don’t think the current draw is anything to be alarmed at.
The fridge operates most efficiently on gas, so the flame shuts off and on as cooling is needed. The electric is less efficient in this application so it tends to run almost constantly to keep up and maintain an even temperature.
__________________
Rob & Amy
2019 Passport 240BH SL (for sale)
2024 Cougar 29BHL (Taking delivery 5/11/24)
2022 Ford F250 7.3L Godzilla Crew Cab FX4
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03-06-2021, 06:36 AM
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#10
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Senior Member
Join Date: Jan 2013
Location: Indiana
Posts: 2,720
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The power converter in your camper (you know, that panel that has all your circuit breakers and fuses).... that thing is always running, it never shuts down unless you unplug from shore power. It' constantly running to charge your battery, to power the circuit boards in your (gas/electric) refrigerator, the radio in your entertainment center (it never shuts completely off), the LED light and clock in your microwave, your television never shuts completely off, your CO2 detecor is powered by your battery - converter also. Add it all up and there is a constant draw on your converter - circuit breaker, not to mention the power the converter needs to run also. Add it al up and it's an easy 300 watts.
Nothing to be alarmed about. The alternative is to shut shore power off, or unplug if you truly want 0 watts.
__________________
2019 Montana High Country 375FL
2014 Chevy Duramax HD 6.6 - 3500 Diesel Dully Long bed Crew Cab
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03-06-2021, 07:29 AM
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#11
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Junior Member
Join Date: Oct 2019
Location: Livingston
Posts: 25
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Quote:
Originally Posted by JRTJH
If you're trying to "eliminate the refrigerator heating element from the mix, why not simply disconnect both the black wires on the control board at J7 and J8 ??? That will effectively remove the "amp drain" of the heating element, simulating the thermistor/control board "turning it off"...
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Just did this and the AC draw goes to 0 watts - same as I see when I turn the AC off with the control button and when I unplug the cord.
Tested the resistance and got 43.8 ohms - within spec.
DC draw still on, but I'm not measuring that and after a few seconds the gas fires up.
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03-06-2021, 08:01 AM
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#12
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Junior Member
Join Date: Oct 2019
Location: Livingston
Posts: 25
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Quote:
Originally Posted by NH_Bulldog
I don’t think the current draw is anything to be alarmed at.
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It's a concern because I'll be boondocking through the summer and will aim for max energy conservation - both battery/ AC inverter and propane.
I have 3600 Wh of batteries and on a sunny day I'll generate more than 6000 Wh solar power. That means I'll have 2400 Wh to spare which I can use to power the fridge with AC during the day which will conserve 6+ hours of propane.
Quote:
Originally Posted by NH_Bulldog
The fridge operates most efficiently on gas, so the flame shuts off and on as cooling is needed. The electric is less efficient in this application so it tends to run almost constantly to keep up and maintain an even temperature.
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Further testing this morning reveals that the gas runs continuously as well. So the problem appears to be that the control board is ignoring the thermistor.
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03-06-2021, 08:06 AM
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#13
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Site Team
Join Date: Jul 2014
Location: Modesto
Posts: 20,357
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Quote:
Originally Posted by ATXCharlie
It's a concern because I'll be boondocking through the summer and will aim for max energy conservation - both battery/ AC inverter and propane.
I have 3600 Wh of batteries and on a sunny day I'll generate more than 6000 Wh solar power. That means I'll have 2400 Wh to spare which I can use to power the fridge with AC during the day which will conserve 6+ hours of propane.
Further testing this morning reveals that the gas runs continuously as well. So the problem appears to be that the control board is ignoring the thermistor.
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That sounds like a good possibiloity. I wouldnt get a new DOMETIC board, I would get a Dinasour brand, I can say from personal experience that they are much better than OEM.
__________________
![](image.php?s=654699a44c3f599c561397c213037f38&u=14512&type=sigpic&dateline=1418489574)
2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.
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03-06-2021, 08:12 AM
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#14
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Junior Member
Join Date: Oct 2019
Location: Livingston
Posts: 25
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Quote:
Originally Posted by dutchmensport
The power converter in your camper ... Add it all up and it's an easy 300 watts.
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I'm running off solar / batteries / inverter+charger and the inverter reports 3 watts parasitic draw from AC-OUT when all my appliances are off. Turn on the fridge (AC) and the draw goes up 305 watts. I know there are also parasitic DC draws but that's not what I'm trying to address today.
Since I'll be boondocking most of the summer every watt matters.
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03-06-2021, 08:13 AM
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#15
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Junior Member
Join Date: Oct 2019
Location: Livingston
Posts: 25
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Quote:
Originally Posted by ChuckS
Food for thought ....
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I get 43.8 Ohms so it's within spec.
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03-06-2021, 08:23 AM
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#16
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Junior Member
Join Date: Oct 2019
Location: Livingston
Posts: 25
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Quote:
Originally Posted by chuckster57
That sounds like a good possibiloity. I wouldnt get a new DOMETIC board, I would get a Dinasour brand, I can say from personal experience that they are much better than OEM.
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I'll be ordering a Dinosaur board today!
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03-06-2021, 12:49 PM
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#17
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Senior Member
Join Date: Feb 2019
Location: Wickenburg
Posts: 3,314
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Quote:
Originally Posted by ATXCharlie
I'm running off solar / batteries / inverter+charger and the inverter reports 3 watts parasitic draw from AC-OUT when all my appliances are off. Turn on the fridge (AC) and the draw goes up 305 watts. I know there are also parasitic DC draws but that's not what I'm trying to address today.
Since I'll be boondocking most of the summer every watt matters.
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If I understand correctly, you're running your fridge on AC off your inverter, instead of running off batteries and propane. Just because you can do that doesn't mean you should, especially if every watt matters. First, the electric heater element in your fridge is less efficient than than propane heater. Second, there is conversion loss transforming your battery DC into AC in the inverter, and then back into DC on the fridge board. Propane may not be as convenient as solar when you're boondocking, but it's worth taking advantage of for cases like this.
__________________
2019 Cougar 26RBSWE
2019 Ford F-250
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03-02-2024, 12:39 AM
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#18
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Junior Member
Join Date: Mar 2024
Location: los angeles
Posts: 1
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Like you, I observed and studied it in order to save power.
Quote:
Originally Posted by ATXCharlie
I’m trying to figure out why my 2652 never stops drawing 300 watts when it runs on AC. It works great - keeps freezer frozen and refrigerator ~34F. It does not have the Climate Control function, so that’s not the issue. I tested the thermistor - get 8980 ohms when it’s in ice water which is within spec.
Is there anything I should test (I’ve got a multimeter) before I just buy a new circuit board for $100 and hope that fixes things?
Any help is appreciated!
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Like you, I observed and studied it in order to save power. I think your refrigerator temperature automatic control device is normal and does not need to be replaced. The heating rod of the DM2652 refrigerator does generate heat at a power of 300W almost all the time. If you have an energy meter with an automatic accumulated time function and check it carefully, you will find that it stops heating for a few hours late at night every day. Depending on changes in ambient temperature, its actual heating time is between 14 and 24 hours. This is too bad for energy conservation. But this is an inherent characteristic of absorption refrigerators, and its energy consumption cannot be improved. I have tried two ideas to improve it, but both failed. One is to wrap the hot tank with insulation material, and the other is to forcibly reduce the power of the heating rod. Eventually, I decided to sell it and replace it with a regular compressor model apartment refrigerator. The daily electricity consumption is only one-quarter of that of an absorption refrigerator. And much cheaper than absorption refrigerators.
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