Thoughts and Ideas on Dometic RM4606 Issues

Lloyd-Vicki · Member

Thoughts and Ideas on Dometic RM4606 Issues

valiant81 · Guru

Hi all; i have had 3 Dometic 3 way fridges in 3 different Jayco caravans. All were next to usless on all energy sorces ! 12 volt while driving, gas while free camping and 240 Volts when able to access 240 power ( at home or in a caravan park. ) They all took several days to settle down and start to cool ( ???? ) and one of the reasons why we also travel with a couple of 40 Litre Engle fridges. My main concern is what does one do if one has a young family and traveling with a fridge that can not even keep milk cold

A couple of years ago i had the 3 way fridge removed and sold it for $ 150.00. I up graded to a 12 / 240 volt compressor fridge. A bit more solar on the roof and another agm battery and good to go. At least the food in the fridge now stays cold and even traveling to Victoria and South Australia in Febuary / April early this year we never had a a problem with the fridge in the caravan staying cold.

Some people on these forums have also swoped out the old 3 way fridge and bought a inverter fridge of simular size to their old 3 way and run that fridge of a small decated inverter and connected to the 12 Volt house battery. This seams to work and work well and of course a increase with solar and battery capacity.

KJB · Guru

Just change it for a "compressor type" fridge and then you can forget all the "3 way" problems . I have been through "3 way problems" several times over the years with various vans (including a fleet of "on site" hire vans ) and campers - (luckily I learnt early not to prolong the problem , replace the 3 way as soon as you buy the van, potential problems solved). All fridges need good , positive ventilation - which may require you to install a small circulation fan behind the fridge with somewhere un obstructed to suck from and exhaust to, in an upward direction .

Are We Lost · Guru

I have a Dometic 4601 ... the same 186 litre size 3 way fridge but a few years older. Mine is now working fine after resolving installation issues and adding cooling fans.

From discussions on here and elsewhere it seems that nearly all installations do not comply with Dometic's guidelines. Very common. You can download those from the Dometic site if you don't have them already. The main points most often overlooked are:

Undersized vents top and bottom to the outside of the van
Correctly positioned top vent that ensures airflow past the cooling fins
No insulation around the back, top and sides

In many cases, addressing those issues will resolve the problem. I also fitted 2 x 120mm 12v fans (Jaycar) to the top vent with a bit of coreflute to better direct air through the cooling fins.

Probably the reason it worked fine at the workshop (if it did) was it was in the shade, or at least shaded on that side of the van. When you park the van somewhere, avoiding the afternoon sun on it will help as well.

A compressor fridge is less finicky. If you only go to powered sites they are a better solution, but if you want to freecamp a wet day with limited solar input means you need an alternate method of keeping the battery charged.

Cupie · Guru

Are We Lost wrote:
I have a Dometic 4601 ... the same 186 litre size 3 way fridge but a few years older. Mine is now working fine after resolving installation issues and adding cooling fans.

From discussions on here and elsewhere it seems that nearly all installations do not comply with Dometic's guidelines. Very common. You can download those from the Dometic site if you don't have them already. The main points most often overlooked are:
Undersized vents top and bottom to the outside of the van
Correctly positioned top vent that ensures airflow past the cooling fins
No insulation around the back, top and sides
In many cases, addressing those issues will resolve the problem. I also fitted 2 x 120mm 12v fans (Jaycar) to the top vent with a bit of coreflute to better direct air through the cooling fins.
Probably the reason it worked fine at the workshop (if it did) was it was in the shade, or at least shaded on that side of the van. When you park the van somewhere, avoiding the afternoon sun on it will help as well.
A compressor fridge is less finicky. If you only go to powered sites they are a better solution, but if you want to freecamp a wet day with limited solar input means you need an alternate method of keeping the battery charged.

As a 3 way fridge user of 24 years or so I agree with this well composed reply.

My main error was to ask for a larger fridge when they were building my van. But the d'heads left the exit vents at a level suitable for a smaller fridge!!! Typical of the Au Caravan construction industry. In fact the installation ignored several aspects of the fridge supplier's instructions.

It took me years to fix it up. Works well now but then I rarely spend long periods in the Tropics with high ambient temperatures.

On the other hand, it is still working after 24 years.

BTW the mention of corflute in one of the replies has given me an idea for yet another improvement to the air flow over the rear of the unit.

Lloyd-Vicki · Member

Thank you "Are We Lost" and Cupie. Great feedback. I had purchased a set of vent fans from the 3D print chap, but these were designed to blow air out of the upper vent. Given that I now have a roof vent, will definitely look at your solution. have them suck air in through the upper vent onto the condenser and help push the hot air out the roof vent.

Are We Lost · Guru

I don't think that is the best solution. What you want is airflow coming in through the lower vent, up through the fins and then out. The airflow should be baffled to ensure it can not bypass the fins on the way out, which should be out the top (side) vent, as well as the roof vent if available. The compartment behind the fridge gets quite hot, and the chimney will burn if you touch it. So you need to expel that hot air, not just cool the fins. When the fans are not running, the rising hot air creates a passive airflow.

Have a quick look to verify that your top vent (not rooftop vent) is above the cooling fins (not below as Cupie discovered in his original setup). The LS300 is the specified vent for that size fridge (490mm x 249mm).

Another common problem I recall now is not fitting the exhaust correctly. It is easy for someone to slide the fridge out but fail to reposition the exhaust tube correctly to blow outside. With the fridge running you should feel it blowing out the exhaust pipe usually mounted in the top vent. Sometimes it takes the fridge being positioned exactly right to fit it, and once fitter then slide the fridge back that final few centimetres.

Have you read the installation instructions?

Dometic Absorbtion Fridge Installation

-- Edited by Are We Lost on Tuesday 4th of July 2023 08:11:22 PM

Lloyd-Vicki · Member

Unfortunately, our installation is not per Dometic's instructions. They state that the lower part of the upper side vent should not be any lower than the top of the fridge, but given the height of the fridge and with the upper vent as high as it can be mounted, one third of the vent sits below the condenser. That is why the service agent suggested fitting the roof vent, but it has made no difference what so ever.

I have checked the heater exhaust and it is emitting heat and very hot to the touch.

Would fitting fans to the lower vent to force air up be better?

2happy · Member

Given that the freezer appears to work fine you might look at issues that are confined to the fridge compartment. Try looking at the fridge door seal (try the sheet of paper test) - if you close a sheet of paper in the door and can withdraw it easily then the seal may be suspect, ie letting cold air escape. OR perhaps the door could be hung incorrectly. I had this happen to me as ours come from the factory with the door "hung incorrectly" - swung from a slightly incorrect pivot point just next to the "true position" (if this makes sense?). To answer one of your other queries the fridge temp is usually taken to be measured on the fin where the thermisistor is mounted.

Lastly, don't have too high an expectation of what the fridge will achieve - you will NEVER freeze water in the fridge compartment (maybe lettuce though!).

Like Are we lost & Guru, I have a properly working absorption fridge after many weeks of googling as I prefer to use the battery power to run things like air fryers and induction cooktop. If you are prepared to persevere and you get a result the pain will be worth the gain.

Lloyd-Vicki · Member

Thank you 2happy said

Are We Lost · Guru

Lloyd-Vicki wrote:
one third of the vent sits below the condenser. ..................

Would fitting fans to the lower vent to force air up be better?

Aha. That appears to be the main problem. My setup is similarly not ideal, but better than that one third.

The downside of fitting fans at the bottom is that you are sucking dust into the compartment, then dampness or worse when it rains. So what dust gets sucked in can turn to mud.

Is there room between condenser and side wall to mount fans? I would put a baffle just under the condenser so air must flow through the fins, then put the fans as high as possible. Feel the fins to see which part is hottest. The specs show the vent measures 249mm, so a couple of 120 mm fans would still do a pretty effective job. Add one under the top vent if needed, or one in each. But try and leave airflow so it can cool passively.

Often, people mount the fans on the condenser itself, which I tried first, but I got better results with two mounted on the vent blowing out.

By the way, when I did mine I first chose two Jaycar YX2574 fans. Quiet but 37 cubic feet /min each was not enough. Then the YX2522. 88 cubic feet / min was a lot better but at 42db, a little noisy. The YX2584 is half way. You might want to check what the specs are for yours. Avoid mounting on a hard surface to minimise drumming.

Edit: 2Happy said "Lastly, don't have too high an expectation of what the fridge will achieve - you will NEVER freeze water in the fridge compartment (maybe lettuce though!)."

Oh yes it can. Absolutely. I have to be very careful not to freeze things. I typically run it on about 1-2 on the dial, although it's been a while since northern Australia temperatures, so not sure what I set it on then. But for say 28 degrees ambient that works.

-- Edited by Are We Lost on Tuesday 4th of July 2023 09:12:14 PM

Lloyd-Vicki · Member

As a result of research, I had installed a baffle between the lower edge of the upper vent and across to the lower part of the condenser to force all rising air through the condenser. But when I took it to the so-called authorised service agent, he tore it out saying that it was contributing to the problem. I thought it made good sense, will re-do it, certainly can't hurt at this stage. Thank you for the fan info.

Radar · Guru

My 2 bobs worth.

Firstly don' t expect to much out of refrigerator. Its definitely not like the home refrigerator.

We found ours runs best on midway on 3 out of 5 on dial. Generally on 4 freezes the lettus.

Secondly we very seldom run our Dometic 4606 on 12 volt between camps, mostly turn the gas off, back on at lunch time etc. It keeps the temp pretty good with it's good insulation quality.

A 2012 model still servicing us well. Our white wine is cold enough to be satisfying.

I did change the 12 volt supply from the tow vehicle to the caravan batteries, mainly because the current draw is very high 22amps and over 14 metres long though an andersen plug is a bit much to expect, now less then 2 metres, much better and appears to be working ok.

Sorry to hear your refrigerator is causing you some grief.

Warren-Pat_01 · Guru

Hello Lloyd-Vicki,
I have a 3way in my current van - not certain what the model is (think it is about 170L) but in our previous Eagle, there was a 90L (RM2350?) 3way fridge fitted. And yes, it was not installed correctly. The air gap above the fridge was insufficient but somehow it worked.

I added two computer fans at the back of the fridge - one at the bottom was set at an angle to blow air up through the fins, the other was at the top & that sucked the hot air out. For power, I used a small 10w solar panel connected to the two power wires from the fans through the bottom vent.
When the hot sun was on the fridge side of the van & we were stationary, I set up the panel & let it all go - with ball bearing fans, there was minimal noise & there certainly was an improvement in cooling.

I've looked at my current van - there is no room anywhere to fit one fan, let alone two!

My issues with changing to a compressor fridge are mainly weight - more solar panels & the sun can have bad days where there is insufficient (as in Townsville these past few days), "just another" AGM battery - where does it go & what do I leave at home to cover this increased weight? Yes, lithium is lighter but there are other issues there too!

Dick0 · Guru

Hi Lloyd & Vicki,

My fridge is the RM4605, similar to yours.

Any cooling problems on gas, firstly start by using the fridge on 240V, which will indicate whether the fridge components are operating properly.

If works well on 240V on 1-3/5 setting, fridge at about 3-4C and freezer at about 12-15C, then most is OK.

Best then to look at gas burner and LPG gas flow. The gas flow adjustment (manual gas shut off valve) is just prior to the gas jet (burner jet). It is a screw just underneath the gas valve solenoid and can manually turn the gas off/on. It must be in the fully open position.

Remove the cover to access the gas flow adjustment. If all working properly you should see a blue flame with no yellow tips and hear the gas burner. If yellow tips then check your stove burners, also, for yellow burner tips. If you are not getting a full blue flame then the LPG gas pressure needs to be adjusted at the gas bottles. There are YouTube videos to show how to do this simple adjustment to the gas pressure.

Bear in mind that you need to have high burner heat to effectively run the fridge on gas.

Also, find out from the Service Agent whether a refrigerant pressure test was conducted.

Lastly, if you get the fridge working satisfactorily on gas, then look at installing cooling fans at the top fridge vent. Another issue at another time.

Yes, I have had issues of fridge operating on LPG. LPG pressure and gas flow adjustments solved the problems, not only for the fridge but also for the Gas Heater, Continuous Water Heater and Stove/Oven.

Lloyd-Vicki · Member

Radar wrote:
My 2 bobs worth.
Firstly don' t expect to much out of refrigerator. Its definitely not like the home refrigerator.
We found ours runs best on midway on 3 out of 5 on dial. Generally on 4 freezes the lettus.
Secondly we very seldom run our Dometic 4606 on 12 volt between camps, mostly turn the gas off, back on at lunch time etc. It keeps the temp pretty good with it's good insulation quality.
A 2012 model still servicing us well. Our white wine is cold enough to be satisfying.
I did change the 12 volt supply from the tow vehicle to the caravan batteries, mainly because the current draw is very high 22amps and over 14 metres long though an andersen plug is a bit much to expect, now less then 2 metres, much better and appears to be working ok.
Sorry to hear your refrigerator is causing you some grief.

Thank you, radar, much appreciated.

We dream of being able to freeze a lettuce. I have to leave ours set to 5 all the time just to keep it below 10degC

I sometimes wonder if ours has any insulation, as soon as it is turned off, the temp starts to climb.

Lloyd-Vicki · Member

Warren-Pat_01 wrote:
Hello Lloyd-Vicki,
I have a 3way in my current van - not certain what the model is (think it is about 170L) but in our previous Eagle, there was a 90L (RM2350?) 3way fridge fitted. And yes, it was not installed correctly. The air gap above the fridge was insufficient but somehow it worked.

I added two computer fans at the back of the fridge - one at the bottom was set at an angle to blow air up through the fins, the other was at the top & that sucked the hot air out. For power, I used a small 10w solar panel connected to the two power wires from the fans through the bottom vent.
When the hot sun was on the fridge side of the van & we were stationary, I set up the panel & let it all go - with ball bearing fans, there was minimal noise & there certainly was an improvement in cooling.

I've looked at my current van - there is no room anywhere to fit one fan, let alone two!

My issues with changing to a compressor fridge are mainly weight - more solar panels & the sun can have bad days where there is insufficient (as in Townsville these past few days), "just another" AGM battery - where does it go & what do I leave at home to cover this increased weight? Yes, lithium is lighter but there are other issues there too!

Thank you for you comments.

Lloyd-Vicki · Member

Dick0 wrote:
Hi Lloyd & Vicki,
My fridge is the RM4605, similar to yours.
Any cooling problems on gas, firstly start by using the fridge on 240V, which will indicate whether the fridge components are operating properly.
If works well on 240V on 1-3/5 setting, fridge at about 3-4C and freezer at about 12-15C, then most is OK.
Best then to look at gas burner and LPG gas flow. The gas flow adjustment (manual gas shut off valve) is just prior to the gas jet (burner jet). It is a screw just underneath the gas valve solenoid and can manually turn the gas off/on. It must be in the fully open position.
Remove the cover to access the gas flow adjustment. If all working properly you should see a blue flame with no yellow tips and hear the gas burner. If yellow tips then check your stove burners, also, for yellow burner tips. If you are not getting a full blue flame then the LPG gas pressure needs to be adjusted at the gas bottles. There are YouTube videos to show how to do this simple adjustment to the gas pressure.
Bear in mind that you need to have high burner heat to effectively run the fridge on gas.
Also, find out from the Service Agent whether a refrigerant pressure test was conducted.
Lastly, if you get the fridge working satisfactorily on gas, then look at installing cooling fans at the top fridge vent. Another issue at another time.
Yes, I have had issues of fridge operating on LPG. LPG pressure and gas flow adjustments solved the problems, not only for the fridge but also for the Gas Heater, Continuous Water Heater and Stove/Oven.

Hello Dick0, thank you for your comments.

Our fridge works equally on either gas or 240v, no obvious change in performance. The freezer seems to be constant at around -15degC, but to get the fridge anywhere near 5degc I have to run it at max cooling.

Nothing was ever mentioned about a pressure test.

May I ask where abouts on the fridge condenser is your temp sensor? Our started out on the far right looking into the fridge. The first service tech moved it in three fins and now I notice it is sitting about the middle.

Are We Lost · Guru

Lloyd-Vicki wrote:
I sometimes wonder if ours has any insulation, as soon as it is turned off, the temp starts to climb.

Just take the cover off the outside top vent and have a look. If it is a Dometic one it has a sliding clip. 2 minutes to check.

Dick0 · Guru

Lloyd-Vicki wrote:
Dick0 wrote:
Hi Lloyd & Vicki,
My fridge is the RM4605, similar to yours.
Any cooling problems on gas, firstly start by using the fridge on 240V, which will indicate whether the fridge components are operating properly.
If works well on 240V on 1-3/5 setting, fridge at about 3-4C and freezer at about 12-15C, then most is OK.
Best then to look at gas burner and LPG gas flow. The gas flow adjustment (manual gas shut off valve) is just prior to the gas jet (burner jet). It is a screw just underneath the gas valve solenoid and can manually turn the gas off/on. It must be in the fully open position.
Remove the cover to access the gas flow adjustment. If all working properly you should see a blue flame with no yellow tips and hear the gas burner. If yellow tips then check your stove burners, also, for yellow burner tips. If you are not getting a full blue flame then the LPG gas pressure needs to be adjusted at the gas bottles. There are YouTube videos to show how to do this simple adjustment to the gas pressure.
Bear in mind that you need to have high burner heat to effectively run the fridge on gas.
Also, find out from the Service Agent whether a refrigerant pressure test was conducted.
Lastly, if you get the fridge working satisfactorily on gas, then look at installing cooling fans at the top fridge vent. Another issue at another time.
Yes, I have had issues of fridge operating on LPG. LPG pressure and gas flow adjustments solved the problems, not only for the fridge but also for the Gas Heater, Continuous Water Heater and Stove/Oven.
Hello Dick0, thank you for your comments.
Our fridge works equally on either gas or 240v, no obvious change in performance. The freezer seems to be constant at around -15degC, but to get the fridge anywhere near 5degc I have to run it at max cooling.
Nothing was ever mentioned about a pressure test.
May I ask where abouts on the fridge condenser is your temp sensor? Our started out on the far right looking into the fridge. The first service tech moved it in three fins and now I notice it is sitting about the middle.

Update for you.

If all works the same on LPG and 240V then I can only suggest the Thermistor (Temp Sensor Probe) is faulty or in an incorrect location.

According to Dometic the Probe should be located in the highest position along the right side fin in the probe holder (under the freezer shelf) for the coolest setting.

My Probe was removed from that location years ago and it comes under the drip tray and only rests upon the interior lamp cover on the right side of the fridge. I suppose it could be secured in this location but I have not had a need to do this.

My fridge temps on 2-3/5 settings is 3-5C fridge and 11-14C freezer.

Remove the Probe from the rear fin location and rest the Probe above the light cover and try the fridge operation on 240V.

Put some ice cube containers in the freezer and put several cans and bottles in the fridge and run the fridge for 24-36hours on 240V.

You may find this to be your problem solution.

Let us know how you go with the test.

-- Edited by Dick0 on Thursday 6th of July 2023 12:47:42 PM

Dick0 · Guru

Lloyd-Vicki wrote:

Hello Dick0, thank you for your comments.

Our fridge works equally on either gas or 240v, no obvious change in performance. The freezer seems to be constant at around -15degC, but to get the fridge anywhere near 5degc I have to run it at max cooling.

Nothing was ever mentioned about a pressure test.

May I ask where abouts on the fridge condenser is your temp sensor? Our started out on the far right looking into the fridge. The first service tech moved it in three fins and now I notice it is sitting about the middle.

Update for you.

If all works the same on LPG and 240V then I can only suggest the Thermistor (Temp Sensor Probe) is faulty or in an incorrect location.

According to Dometic the Probe should be located in the highest position along the right side fin in the probe holder (under the freezer shelf) for the coolest setting.

My Probe was removed from that location years ago and it comes under the drip tray and only rests upon the interior lamp cover on the right side of the fridge. I suppose it could be secured in this location but I have not had a need to do this.

My fridge temps on 2-3/5 settings is 3-5C fridge and 11-14C freezer.

Remove the Probe from the rear fin location and rest the Probe above the light cover and try the fridge operation on 240V.

Put some ice cube containers in the freezer and put several cans and bottles in the fridge and run the fridge for 24-36hours on 240V.

You may find this to be your problem solution.

Let us know how you go with the test.

-- Edited by Dick0 on Thursday 6th of July 2023 12:47:42 PM

Possum3 · Guru

Tips to keeping 3 way fridge cold;

Park with fridge side of van in the shade.

Ensure caravan is level.

Ensure flue is clear of cobwebs and dust.

Open flaps (doors) behind fridge. If no flaps fitted ensure (breathable) awning fitted to fridge side to shade fridge.

Don't have fridge half empty/full - small plastic bottles of water great to prevent voids.

Prepack foodstuffs in zip lock bags - particularly food in freezer compartment.

Don't leave fridge door open (window shopping).

Ensure fridge closed in locked position.

Defrost fridge regularly.

Set fridge at level 3, - use level 4 only for initial cooling.

Preplan meals to ensure fridge is opened for a minimum amount if time and times.

Stretch60 · Senior Member

With some research I'm surprised that people don't order thier vans with a compressor fridge installed. I have been on this forum for a few years now and have read many stories of woe with 3 way fridges. I was lucky enough that our second hand van came fitted with brand new novakool 12v only fridge. Back in January 2019 in lightening ridge ambient temperature was around 48 degrees and I was pulling ice cold beers out of the fridge.

deverall11 · Guru

Our previous van had what was referred to as an 'analog' fridge. It worked just fine.
Upgrade the van and end up with 'you beaut digital' fridge. The only time this contraption
demonstrated to be with specs was at the Dometic agent.
Installing a fan at the top vent to help suck out the heat did improve things.
At the end of the day, IMHO, these new fandango units are marginal at best and next to
useless in the middle of a hot Australian summer.
Did attempt to swap the unit for our old 'analog' unit but was refused.

Dick0 · Guru

These latest fridge/freezer models are over $3000. Why would anyone CHOOSE to have one in their van.

You can get a 12/240V compressor 180-190cl fridge/freezer much cheaper and with the savings you could update the solar/battery system.

Unfortunately, my Dometic RM4605 works a treat, after modifications, and just won't die!

Alas, I will wait until that day as selling the current fridge, has to date, not been possible. Just no takers.

-- Edited by Dick0 on Saturday 8th of July 2023 10:22:59 AM

deverall11 · Guru

Dick0 wrote:
These latest fridge/freezer models are over $3000. Why would anyone CHOOSE to have one in their van.
......

-- Edited by Dick0 on Saturday 8th of July 2023 10:22:59 AM

Unfortunately sometimes if not all the time the dealer selling the van refuses to accommodate you with

some 'non-standard' accessories. Fridge is one, disc brakes in another but to nam a few examples.

Dick0 · Guru

Hi Lloyd-Vicki,

Any progress in solving your fridge problem?

Lloyd-Vicki · Member

Sorry for delay in responding, we are now on the road. Further issues have arisen, our swift hot water heater won't run on gas. But I digress. After complaining to dometic that we paid to have a roof vent installed to apparently improve heat dissipation and it making no difference, they sent us a copy of the service reps report. They stated that they connected the heater directly to 240v and were getting negative temps in the fridge, so that told them that was all ok with the cooling system. But failed to explain why I have to keep the fridge on max to keep it below 10degC. As someone suggested it might be detrimental to the efficiency, I dropped it to the middle and the temp just climbed into the teens. To me this points towards the temp control system. But I am just a dumb customer.

Dick0 · Guru

Lloyd-Vicki wrote:
Sorry for delay in responding, we are now on the road. Further issues have arisen, our swift hot water heater won't run on gas. But I digress. After complaining to dometic that we paid to have a roof vent installed to apparently improve heat dissipation and it making no difference, they sent us a copy of the service reps report. They stated that they connected the heater directly to 240v and were getting negative temps in the fridge, so that told them that was all ok with the cooling system. But failed to explain why I have to keep the fridge on max to keep it below 10degC. As someone suggested it might be detrimental to the efficiency, I dropped it to the middle and the temp just climbed into the teens. To me this points towards the temp control system. But I am just a dumb customer.

Have a look at my earlier post regarding re-locating the fridge temp sensor probe as a test.

Lloyd-Vicki · Member

Thank you for the suggestion to move the sensor, but it has been in several positions now with no significant impact. Looking into the fridge, it started on the far right half way up. Then the first tech moved it in three fins. After some research I pushed it up to the top. The latest tech has moved it further to the left to about the centre.