Contents:  FRIDGE.

1. Motorhome Fridge   Hints and Tips from Dometic. 2. Changing the gas burner in the fridge
3. Fridge Controls 4. Operating Instructions  5. Circulating Thermal Fan Modification For the Fridge.[Using a Velleman-Kit Mk 138]
 6. Removal of the 230 Volt Fridge Element 7. Fridge Draughts 8. Dometic Q & A faults 9. Fridge faults and how to cure

This information is credited to Darren's site, as of July 2006 his site is unavailable, but he might respond to: darren@caravanfaultfinder.co.uk 

another search at: www.caravanfaultfinder.co.uk

The "Faultfinder" is a site for those who would like to understand the workings of the Motorhome fridge. Darren has illustrated the working of the fridge in actual motion, this is quite a novelty.

Darren make's it clear if you don't have the skills, do not attempt repairs to electric and gas appliances.

I have included notes from my own experience, full information is recommended from Darren's site.

Technical Data of the RM4200:

Electrolux fridges with just 3 degrees tilt tolerance include models RM122, 123, 212, 212E, 4206, 4207, 4200, 4201

The fridge in the 'Wanderer' can be run on 230Volts AC, 12Volts DC, or LPG gas. The controls for operating the different methods are described and illustrated above, on the 'Fridge Control' sketch and the '12Volt and 240VAC Controls sketch.'

If the flame goes out on gas operation, the safety device which is placed over the gas flame monitors this, and will turn off the gas supply. Should this happen check the gas supply at the cylinder and repeat the start up procedure. It has been found if the gas is low, this causes a low pressure which will not light the gas even though the gas grill will activate!

In my 'Wanderer' it is fitted with a RM4200-S fridge. To light the gas requires the red press button to be depressed to create a spark at the burner head.

To monitor the flame, viewing is done at the fridge tube interior, at the bottom back.

STARTING THE FRIDGE
Caution: Only use one supply source at a time.

LPG operation. See the above sketches for the controls.

After a period of layoff the gas pipes need to be purged.

To start fridge gas:

a. Open the gas supply valves, at the cylinder and the valve close to the device. If the gas cylinder is low, it is possible it will not operate.

b. Check the RED 12volt DC  and the GREEN 230Volt AC  switches are off.

c. Turn the gas control knob  to maximum.

d. Press the gas contol knob and hold it in position.

e. Press the RED knob about 3 times, to activate the Piezo Igniter at the flame Head.

f. Check the flame viewer at the bottom back of the fridge.

g. If alight, old the control on for another 10 seconds, then release it. Check the flame holds on! If not repeat the proceedure.

To turn off the gas control, just turn the gas control knob to the off position. In the off position the knob will release it self out.

To start 230Volts AC mains operation:

a. Turn the Knob on the left hand side of the control panel, next to the GREEN switch,  to the highest position.

b. Turn on the GREEN switch.

To start 12Volts DC. [ Used when engine running only] 

a. Making sure Gas and Mains are off, turn on the RED switch. 

There is NO thermostat control for the 12Volt operation.

In WINTER it is advised to fit the Electrolux winter vent covers to ensure the fridge coolants, close to the vents, do not freeze up!

During layoffs it is also advisable to ensure the winter vent covers are fitted.

When travelling make sure the door retaining catch is secure, by pressing down the knob at the top of the door. It has two positions one for travelling and the other is used to keep the door ajar during lay up periods.

If the door is closed during layup periods, the fridge will take on a smell which is hard to eliminate.

At the interior, top back of the fridge, can be seen cooling fins. Make sure these are not blocked up with stored food, as this will reduce the effiency of the fridge and also cause hot spots which melt food.

When defrosting the fridge, do not use hot appliances to do this. The plastice walls will melt or be mishapen making the fridge un-useable.

Clean the fridge with little Bicarbonate of soda in warm water, approximately One teaspoonful to a bowl of warm water.

Never use detergents, scouring products or strong smelling polishes. The plastic will hold the odour and taint the food.

Check the following points from Dometic, should the fridge not operate satisfactorily.

During winter draughts from around the fridge are a continuous problem, and discussed in Motorhome Forums many times.

The problem is easily resolved, but I think should be done by the coach builder in the first place.

My solution was to place at the rear of the fridge, on the base plate, a right angled horizontal piece which spans the bottom of the fridge. On this piece I placed a window draught protector strip. See the pictures below.

At the vertical edges, left and right  I placed more window draught protector.

At the top, in recent years the coachbuilders have noted the pleas of the fridge manufacturers and placed a deflector plate to deflect the hot air produced by the fridge. In fact mine has a sponge piece fitted to seal the deflector plate eliminating the top draught. The problem is, this is stuck on, and when the fridge is hot this piece slides down and opening the back to a draught!

I have screwed a plastic piece across this sponge to hold it in place.

The gaps mentioned above are illustrated by red arrows, and should be filled to eliminate interior draughts.

Try this link for useful information on the fridge: http://www.a-tconsulting.co.uk/caravan_tech/fridges.html

For those who have problems with their fridge, then click on the link below for direct access to the Dometic site and their help advice pages.

http://www.dometic.co.uk/

Dometic,
Electrolux Leisure Appliances

PO Box 88
Oakley Road
Luton  LU4 9QQ
www.electrolux.com/caravan

I acknowledge that this page contains answers to common questions handled by Dometic, support staff, along with some tips and tricks that they have found useful and presented here as questions.

Typical Frequently asked questions:

1. My fridge does not work properly. What should I do? 

2. I am having problems running my refrigerator on any energy source.         

3. My fridge does not cool at all.

Are the fins hot?

4. The freezer compartment seems to work, but not the fridge.

5. My fridge normally works OK but not when the weather is hot.

The worktop is hot or warm ...

The worktop is not hot...

6. My fridge works OK in the UK but not when I go to France, Italy  or Spain...

7. I am having problems running my refrigerator on ... 

    ...on 12 Volt 

    ...on gas 

    ...on mains 

8. I cannot light the gas

9. There is a funny smell or there is black soot on the outside of the flue.   

10. The fridge works satisfactorily on mains but not on gas... 

These answers give you some ideas as to the most speedy and cost effective solutions. We have tried to make these explanations as simple and as non-technical as possible. If you can’t understand them you will need to get professional help. A few words of caution.

Before you start:

If your Electrolux refrigerator is less than one year old it is still under warranty (proof of purchase required). In this case we recommend you call out a service engineer who will repair it free of charge. Contact us for information on your local Electrolux Service Force.

Make sure your caravan and with it your Electrolux refrigerator are not tilted excessively, within 6degrees, otherwise the fridge will not work even if everything else is in perfect condition.

Make sure you have the correct energy sources available that you are experiencing problems with.

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I am having problems running my fridge on any energy source...

My fridge does not cool at all

Are all your energy sources available!

Check the fins at the back, top of the cooling system; they should be hot. If the fridge has been on for some time there should be some heat coming out of the top vent. To be sure remove the top vent and carefully feel the fins at the top of the fridge.

 Are the fins hot?

Fins hot: IMPORTANT, Is the fridge tilted excessively?

No

Make sure the fridge is not tilted excessively; if not, the cooling system is probably faulty and needs replacing. Contact us and we will help you to contact Electrolux Service Force in your area.

Yes

Park your caravan on a level surface and see if your refrigerator works. If not, start again from top.

Fins at the rear, not hot: The fridge is not getting any energy, whether gas or AC volts.. The problem could be a combination of problems on all energy sources, but most likely the cooling unit has failed and needs to be replaced. Please Contact us

The freezer compartment seems to work, but not the fridge...

The reason is likely to be a weak cooling unit, but it may also be possible that the evaporator plate in the fridge is loose. Try to fasten the screws with an Alan key; if that does not help, take the evaporator plate off completely. There should be nothing between the evaporator plate and the mastic behind it.

My fridge normally works ok but not when the weather is hot...

Feel the surface over the fridge, normally a worktop or a sink:

The worktop is hot or warm...

The fridge is not sealed in properly. If you would like to try to fix this yourself we can send you a DIY article "Hot worktop cure article".

The worktop is not hot ...

Try running the fridge on other energy sources. If the fridge still does not work properly and the fridge is level enough the cooling unit is probably faulty and needs replacing.

My fridge works ok in the UK but not when I go to France, Italy or Spain...

I am experiencing problems on all energy sources...

See Q1

The problem only occurs in mains operation...

This is sometimes a problem in Southern Europe where the electrical supply regulations are not so stringent as in the UK so there is sometimes insufficient voltage. You will need to run the fridge on gas.

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I am having problems running my fridge on ...

...on 12 volt

Any fridge takes a while to cool down and your caravan fridge is no exception. So you should pre-cool your fridge on mains or gas before your journey, using the 12-Volt to hold the temperature down.

The 12-Volt is designed to operate only when the engine is running in the base vehicle or tow car. You need to make sure that there is a 12-Volt supply and that it is 12 Volts at the fridge. If you have a suitable instrument measure the voltage across the heating element. If there is less than 12 Volts there is a problem with the supply. It could be a high resistance (dirty) connection. Alternatively the supply wire could be too small. As a guide it must be at least 2.5 sq mm; more in the case of long runs. You should consult your handbook for more information.

If you are sure the fridge does not work properly on 12 Volt, but does work OK on 230v and gas and there is at least 12 Volts across the heating element it could be that the element itself is faulty.

The technical way to check – pull the fridge partly out of its recess and disconnect the 12 Volt supply. Now measure the resistance of the element. It should be approximately 1.5 ohms. This need not be a precise measurement, if it has failed it is likely to be either a short or open circuit.

The non-technical way to check – Make sure the fridge has been switched off for at least a few hours. Now remove the top vent and make sure the top of the cooling system is cold. If you have a caravan you will need to connect it up to your tow car. Now switch on the 12-Volt and start the engine. Leave it running for at least 30 minutes. Now check the top of the cooling unit. If it is still cold there is a problem on the fridge’s 12-Volt circuit or the element itself.

...on gas

I cannot light the gas...

First it is a good idea to make sure that gas is getting to the fridge. There should be a gas cock in the supply pipe adjacent to the fridge, make sure this is turned on. Now light one of the burners on the hob. This confirms gas is getting into the supply pipes. It also helps clear some of the air from the pipes if the fridge has not been switched on for some time. If your gas bottle is below a quarter, it's possible there is not enough pressure to ensure a steady flame.

Next go trough the lighting procedure:

1. Piezo Ignition

2. Electronic Ignition

Piezo Igniter:
1. Set the temperature control to a mid-setting. Now push the knob and hold it in (this is the flame failure device). Hold in for around five seconds. The flame is viewed through the observation glass. At the bottom back, in my fridge.

2. Now depress the Piezo igniter rapidly three or four times in rapid succession. Continue holding in the flame failure device and look through the viewing glass to see if the flame is alight. If it is, then hold in the knob for about twenty seconds and release it. The flame should stay alight. If it continues to flame this can be confirmed by placing your hand over the outside vent, it will feel hot.

If it goes out repeat the procedure. If the flame will still not stay alight there is a problem with the flame failure device or the thermocouple. The repair is a professional job. If you are a good DIY person all it needs is to replace the piezo activator, cable and ceramic sparker close to the flame.

If the gas will not light at all, despite repeated attempts, there is a problem with the burner. The repair is a professional job. You should ensure that the gas system has a complete service. This involves cleaning the gas central tube and burner and replacing the jet (this should always be replaced, never cleaned, as there is a risk of enlarging the orifice).

On my fridge the flame is very difficult to see. By coincidence I went outside and found the vent to be hot, indicating the fridge was working on gas, even though the flame was not seen.[ Changing the gas burner has cured this problem. See above.]

The other problem might be the chimney needs cleaning - access is usually from the upper ventilator grill and also removing the exhaust outlet cover. The top half of the exhaust pipe is a slanting 'T' shape and when removed from the fixed tube of the insulated 'chimney, there should be a wire bent over as a hook laying in a slit in the tube. Pull this up and down a few times (on the other end is a twisted piece of flat steel that causes the hot gasses to swirl as they rise - this also 'sweeps' the chimney when raised and lowered) - you should only have to do this no more than once a year, maybe only every 3 or 4 years.
[ This excellent advice came from Ted C. ]

Electronic Igniter:

1) Set the temperature control to a mid-setting.

2) Now push the knob and hold it in for around five seconds (this is the flame failure device).

3) Now switch on the electronic igniter. Continue holding in the flame failure device and look through the viewing glass to see if the flame is alight. If it is then hold in the knob for about twenty seconds and release it. The flame should stay alight.

Note: do not switch off the Electronic Igniter; it will automatically relight the flame in case it blows out.

If the flame does not stay alight repeat the procedure. If the flame will still not stay alight there is a problem with the flame failure device or the thermocouple. The repair is a professional job.

If the gas will not light at all, despite repeated attempts, there is a problem with the burner. The repair is a professional job. You should ensure that the gas system has a complete service. This involves cleaning the gas central tube and burner and replacing the jet (this should always be replaced, never cleaned, as there is a risk of enlarging the orifice).

There is a funny gas smell or there is black soot outside of the blue...

There is a problem with the burner which should be given a complete service.

...on mains

...only when I am in France, Italy or Spain...

This is sometimes a problem in Southern Europe where the electrical supply regulations are not so stringent as in the UK so there is sometimes insufficient voltage. You will need to run the fridge on gas.

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The fridge works satisfactorily on mains but not on gas...

There is a problem with the burner which should be given a complete service.

A common fault is the 'chimney' becoming sooted up - this is a small (about 1" dia) tube at the top rear of fridge that should be accessible by removing the upper external vent (you DO have 2 vents don't you?) - hanging over the top edge of the chimney should be a piece of wire (about 1/16th) bent into a hook so that it stayes in place - on the other end is a piece of twisted metal that creates a vortex for the hot gases - this piece of metal also acts as a flue brush - just pull the wire up and ease it back down a few times and you will 'Sweep' any 'Sooty' deposits loose and the flue will be clear.

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Circulating Fan For the Fridge

    The fridge operates by absorbing heat and dispersing it at the rear, which is then vented outside. 

    On a very hot day in Spain, the air circulating in at the bottom vent is hot. The circulating top vent temperature can be little different. This causes hot spots, inside the fridge, and melting at these points.

    The solution is to ensure the vent circulating plate is secure and does not vent into the van interior.

     In the Wanderer there is a sponge piece stuck on to ensure hot air is not vented into the interior of the van. It keeps falling off as the glue melts from the fridge heat! I have screwed an aluminium strip horizontally across the sponge to secure it.

    The other solution for poor circulation, is to add a fan at the back of the fridge, to the top vent and force the air out.  The fan is controlled by a heat sensor which controls the fan on/off state.

    There are one or two solutions advertised by Motorhome dealers in the UK. I chose this method.

    Maplin's the well known electronics dealer is selling a Velleman-kit MK138.  This is a module with a kit of parts for constructing, to control the fan. Priced at £4.99 in Mar. 2003. 

     The fan is from Maplin's computer parts working at 12volts. This cost me £4.99.  The construction is quite easy, even for those who rarely pick up a soldering iron, and the kit is of a high standard.

     With the module complete it only needs 7 wires to complete the thermostatically controlled fan. An on/off switch was incorporated, for those quiet nights when the fan would seem noisy. See illustrations below:

I have located the Negative temperature resistor[ 10kNTC] near the back of the fan on a bracket. The wires of this component are a little brittle and liable to snap with vibration experienced in the Motorhome. So I made up a base plate to secure it, as seen in my drawing below.  As this is a key component it must be secured. See sketch below.

During our tour of the continent in the summer of 2003, it was found that the NTC was too sensitive. The fan would come on at the slightest movement of warm air. As the variable adjustment was at it's maximum travel, this phenomenon could not accommodated.

Also D2 failed, cutting off voltage to the module, as a stop gap this was short circuited.

A modification of the components were done and this page updated.

June 2003. The modification was;

1. D2 has been replaced with a 1N4004 diode which will allow more current to pass.
2. R6 Changed to 100kohms and R5 to 56Kohms. This has brought the Variable Temperature control to the Mid position and reduced the sensitivity.

There is another alternative which I am considering. This eliminates the complexity of the installation.

Maplin's are now selling a computer Thermally controlled fan. Part No: A12AB. This has a built in temperature sensor with a variable fan speed. It increases it's speed as the temperature rises.

Maplins web site can be seen at: www.maplin.co.uk or tel: 0870 429 6000

The computer derived fan was so quiet that I had to feel the air flow from the vent to ensure it was operating! No disturbed nights sleep with this one. Having said that it turned off automatically at night!

Having returned from South of France, Sept 2005, where the temperatures never came below 20C, the fan did not behave as intended. Most unreliable! I shall modify it and update this page when completed.

Update:
Regarding the above comment, this was due to some of my soldering dry joints.

Spring time is the time of year when I start checking the Motorhome.

I made a special check of the Fridge this year[ 2006 ], only to find it did not freeze as expected.

The fridge operates on 12Volts from the engine while running. Gas when not running, and when no mains voltage available. Also on 230VAC volts from a hook-up.

The 12volts, 230 volts and the gas function is to produce heat in the fridge. This heat warms up a cocktail of liquid chemicals at the back of the fridge. These chemicals, of which Ammonia is one, then circulate through tubes. One set of tubes go into the fridge to the freezer compartment. This circulating chemical absorbs the heat from the fridge compartment cooling it.

Using my Infra Red Thermometer, I found from a resting non operating condition of 9degrees C, within 1/2 an hour it had reduced to -8degrees C.

  

Things to check, make sure the Motorhome is level. 

My fridge has only a 3degree tolerance, so how the van is levelled is important;

1. Check the voltage is going to the 12Volt element when the engine is running.

2. Hook up the 230VAC mains and check the voltage is reaching the 230v AC element.

3. Check the fridge gas alights and remains on. 

If you find the above checks are not functioning then this is how I did it. 

I assume the reader has some knowledge of how to use a volt meter.

Para. 1. To carry out this check. 

In the engine compartment, the 12volt battery switched relays are usually installed by the Coach builder. Check the voltage from one of the relays.

When the engine starts have you battery volts to the fridge? 

If so turn, return to the fridge.

Check the freezer compartment and ensure it is getting colder. 

If not, turn off the engine, remove the screws that secure the fridge to the frame.

Take off the vents at the outside wall of the Motorhome.

Remove the tubular chimney vent which can be seen on the top of a aluminium tubular casing to the outside.

Now ease the fridge out of it’s frame for about 150mm, until the wiring at the top of the fridge can be seen.

Restart the engine.

Check the 12volts at a junction terminal. It is wise to turn off the mains while doing this. As in my Motorhome, the Mains voltage is received direct from the fuse box.

If you have volts at this point, leave the engine running, then make a note of the cable covering, feeding the 12volts.

Go to the back of the fridge and feel the point where the noted cable covering goes into the aluminium tubular casing. It should start to feel warm. If it is, then that 12volt element is OK. I used an Infra Red Thermometer which shows the change of heat instantly. This saves scorched tips of fingers. If there is no change then a fault has to be considered.

Turn off the engine.

Return to the junction where the 12volt input is, Take off one terminal and do a resistance check of the element. It should be approximately 1.5 ohms.  If it is open circuit then you have a fault. Check the cable feed is OK before condemning the element.

Para 2.

Turn on the mains and check the 230VAC is present at the junction terminal.

If it is, as before, note the cable covering the mains cable and go to back of the fridge and note where this cable is going into the aluminium tubular casing. Check whether the area around the cable is getting warm. If it is then no problem. Check the freezer compartment and ensure it is getting colder.

If not, then you might have a problem.

Turn off the voltage at the mains switch box and do a resistance check of the mains voltage element. If none then you have a faulty 230voltsAC element. Check the cables are OK before condemning the element.

Para 3. 

Checking you hand book and using the instructions on how to light the gas. Go to the rear of the fridge and ensure the gas remains on. i.e. a flame can be seen.

Carry out the temperature checks in the freezer compartment, ensure it is getting colder.

If after carrying out the above checks and the voltages are correct and the gas is lit and stable, and the freezer compartment does not get colder, then it’s possible the chemicals in the tubes are not stable with perhaps air bubbles stopping the circulation.

If so, then the fridge has to be removed, and the favourite method used by the repair man is:

1. Turn the fridge upside down. Leave for an hour.

2. After the hour, turn the fridge upright. Then leave overnight.

3. Next morning, there’s no need to install the fridge for this test. Level out the fridge horizontally and vertically.

Connect a spare cable to the mains element and plug into the mains. 

Check the freezer compartment resting temperature. 1/2 an hour later you should see freezer compartment changing and getting much cooler.

If after all that it does not cool then you have a problem! It is time to spend money!

HINT:  When you remove the fridge, make a note where the cables are located. Make a drawing or use your digital camera. There's nothing worse than getting back to the job at a late date to wonder are the cables correctly fitted!
When the fridge is 1/2 way out, you have to remove the gas pipe. Ensure the gas is turned off before doing this.

When assembling later, place some jointing compound on the threads of the gas joint nut. Not too much or it could be carried to the gas burner and block the  gas jet.