So here is the basic check list to go through, which should narrow it down.
But first a few words about different fridges. The major manufacturer is Dometic, which used to be called Electrolux. Because I am primarily concerned with pre 95 classic Hymer motorhomes, I am only really concerned with the fridges that were installed in those vans. Modern fridges are quite different, and usually have some degree of electronics in them. This article does not cover those. The type of fridge most common in classics is an Electrolux/Dometic with two switches on one side - red and green, illuminated, for 12v or 220v, 2 or 3 control knobs, and another small illuminated red switch on the other side that flashes when pressed - the ignition switch. Similar to this one -
But first - the obvious stuff you can try if you are in a field with warm beer ...
Take off the bottom fridge vent panel outside, so you can see the burner box If you have a screwdriver, remove the tin box around the burner. Now tap and blow and brush as much as you can to try and shake things up a bit - you could well be lucky and dislodge a bit of dust that is causing the problem. If you have no ignition tic - check the connections as suggested below.
If the weather is hot, and the fridge is simply not performing, but you can feel heat coming from the top vent outside (which means you have a flame), then take off the top vent as well, which will increase the air circulation. If the sun is beating on that side of the van, try and turn the van around, or erect a shade. If the fridge works OK overnight but not in the day, then all it needs is better air circulation in hot weather.
The minimum tools you need are a philips screwdriver, a spanner for the gas nut, and either an adjustable spanner or grips to grip the square burner body. (see video - link below).
Is it working on 220v
This is the first question to always ask and answer. If the fridge is working OK on any of the 3 power sources, 220v, 12v or gas, then that means that there is nothing fundamentally wrong with the refrigeration mechanism, and generally means that the fridge can be fixed.Does it tic tic tic?
So the next port of call is the ignition system. On most old fridges this is a red flashing switch which you press - it flashes, and then goes out when the gas lights up. If you press the switch and nothing happens, the first thing to do is to work the switch as hard as you can, many times - ie flick it on and off with (sensible) force. It could just be that the switch is getting tired - it is over 20 years old and spends long periods of time doing nothing. It only needs a tiny bit of dirt or corrosion on the contacts to make it fail - working it hard can help it to self clean.
These red switches have been known to fail. Replacements are available, and they are a generic switch available online, although if you buy a Dometic one it will match perfectly. To test and replace the switch you basically need a multimeter and know how to use it. Ask of the group for more advice.
Some older fridges have a push button manual ignition which you have to push hard to produce a spark. The only way to check these is to go into the back of the fridge and physically check for a spark - see below.
You may have to go outside and put your ear to the lower external vent to listen for the tic tic of the spark.
No flash or tic at all - but it used to work OK last time ...
This is usually down to lack of power for the ignition circuit. Most classic Hymer fridges have 2 12v feeds - one which is permanently connected to the leisure battery for the ignition, and one that is connected to the alternator via a relay which is to power the 12v heating element which only works when you are driving. They are separate circuits. Both of these circuits are fused, so look for a blown fuse in the fuse panel. On most classic Hymers, pre 95, the fridge ignition fuse is number 2, second one down, on the same same circuit as other stuff in the vicinity of the kitchen - so if you have kitchen lights or fan also not working, then it's the fuse.
But if it's not the fuse, then one of the commonest faults is old corroded 12v connections. Take a look at this photo and you will see what I mean. So you need to remove the lower vent, and look for a similar connection. If it looks dirty, clean it. If you are lucky, your ignition will spring back into life. If you are unlucky, and the 12v feed is clean, and you still have no spark, then the ignition unit is suspect, or the switch itself. Both are replaceable. The ignition unit usually means the fridge has to come out, the switch can often be replaced easily from the front panel - both these jobs you can attempt if you have basic DIY skills, but if not maybe best to call in an engineer.
This pic shows a very badly corroded 12v connection! The location of the connector blocks varies from van to van, so if you don't immediately see it, get in there and search with a torch.
Does it flash and tic but fail to light?
If the switch is flashing, and you can hear the tic, but it doesn't light, then it's time to remove the outside vents and look for the spark. This means you have to expose the burner. You will find the burner at the bottom of the chimney/flue inside a thin metal tin box. The tin box is easily released by a couple of obvious screws.
In this picture you can see the tin burner box which covers the burner. You can also see various electrical connections - all have to be checked - every van is different.
This pic is taken from below showing the main components of the burner
Now you can see the burner - see picture. The end of the burner that is directly under the flue, held there by a single screw, is the burner crown. This is a tiny gas ring about the size of a small coin that should produce a blue flame about 30 to 40mm tall. Protruding into the area of the crown you will see two finger like things. One of these is the ignition spark electrode - the one with a porcelain body, and the other is the thermocouple. The electrode is fed by a wire, and this wire goes to an ignition unit which is usually up out of sight. To make it easier to see, you can undo the single screw that attaches the burner to the flue, and pull the burner towards you so you can see inside - there is enough flexibility in the feed pipe to allow this. Then get somebody inside the van to operate the ignition. You need to see a healthy spark between the electrode and the burner crown - it's almost identical to the way an electronic cigarette lighter works.
In most cases, you will see a decent spark. You might even get a flame - if you do, see "low flame" below. If you don't see a spark, but can hear a tic, or the spark looks weak, look for obvious signs of damage or wear. The end of the electrode could be corroded, or the feed wire might be worn and the spark is jumping to ground somewhere, or the wire might have come loose from the back of the electrode, or be corroded.
Another trick you can try is to light the flame manually - with somebody inside pressing the gas knob, offer up a lighted match or lighter to the burner. If it lights and you have a healthy flame, that stays in, then that proves that the problem is with the ignition and not the gas or jet.
You have a good ignition spark, but you are only seeing a small flame, or no flame.
As already mentioned, a healthy flame should be about 40mm tall, blue, and give out a very gentle roar. A low flame will be yellow and candle-like and float about in the breeze, and be silent. The commonest cause of a low flame is something restricting the gas flow.
However it can be difficult to see the size and the quality of the flame in daylight, so be prepared to return to the problem either in darkness, or at a pinch, get somebody to hold a big towel or blanket over you for shade so you can get a good look at the flame.
There are 2 possible causes for a low flame. The first is a blocked jet - see below. The second is that dirt and dust and soot have fallen down the chimney/flue onto the burner crown.
The easy fix is to blow air onto the burner - either with compressed air if available, or by getting up close and blowing - or a bicycle pump. You can also tap and shake the burner. This is usually enough to dislodge any dirt, and if you are out and about on holiday and desperate is the first thing to try. If the results of your efforts are a bigger flame than when you started, then you can put everything back together and hopefully the problem is solved. It can be that easy, if you are lucky!
If not, then you have to remove the burner for deeper cleaning. To do this you grip the square body of the burner with a spanner, and undo the gas feed pipe nut. Then you undo the single screw that holds the thermocouple and electrode in place via the small triangular shaped metal clamp. Take care not to use too much force and make sure you don't damage either the wire feeding the electrode, or the thin copper tube feeding the thermocouple.
Linked at the bottom of this article is a Youtube that shows you exactly how to do this - although in the video, the engineer does not remove the electrode or thermocouple - it's up to you.
Situated in the end of the gas feed pipe is the jet - this is a delicate thimble of thin metal with a tiny hole in it. This allows just the right quantity of gas through, which is then mixed with air through the two side opening holes, then travels down the hole in the body of the burner to the crown, where it should produce the required good flame.
The ideal way to clean the jet is again with compressed air, but blowing and brushing with a hair brush - like a paint brush - is also good. The golden rule here is that under no circumstances must you use anything metallic. Never use a pin or needle. If you open the jet even by just a fraction, you will ruin the carefully metered gas air mixture and create a serious health hazard.
The jet might not come out as easily in the video - in fact it can get stuck so tight that nothing short of brute force will get it out. In this case it is best to clean in situ as best you can. 9 times out of 10 whatever is blocking a jet will dislodge quite easily with a brush or a tap or a blow. Then reassemble and reconnect the gas. Hopefully now you should see a healthy flame.
In extreme cases you may have to replace the jet - make sure you get the right jet - most pre 95 Hymers are 50mb gas pressure, so need a 50mb jet. Swordcrown Caravans are a decent knowledgeable supplier of jets and fridge spares.
Another way forward is to consider replacing the entire burner assembly. They are available from suppliers and eBay for around £50. This is particularly advised if your old burner is literally a rust bucket. Just make sure you order the correct gas pressure - most pre 95 classic Hymers are 50mb. Most UK and post 95 EU vans are 37/30 Mb, so these components are much more common. Do NOT be tempted to fit a 37mb burner/jet to a 50Mb fridge. Do it right!
On reassembly of the gas feed pipe, check you have a good gas seal by brushing soapy water around the nut and look for tell tale bubbles, while at the same time somebody inside is pressing the gas knob so that gas actually flows - you need the gas on in order to perform the bubble test properly.
Closeup of a burner with the jet removed.
If after cleaning the burner and jet, and checking the ignition, you still have no flame, then you are getting into the realms of more complex repairs. It could be that the main gas valve on the top of the fridge needs replacing. This is located behind the main gas knob - the one you keep pressed while lighting the gas.
If you get a flame, but the flame goes out when you release the knob, then the thermocouple is suspect. Again this could mean fridge out, but it is an easy job - either for you if you are confident, or a fridge mechanic.
And that is just about it for "fridge not working on gas" - as long as it works on 220v, then 9 times out of 10 it is either the 12v feed to the ignition, or dirt in the burner or jet.
Corner fridges
A note on corner fridges - if your fridge is in the back corner of the van, you may have vents that are on the side, and you can't get access to the burner. Double check for other means of access - there is sometimes a panel you can remove near the light cluster or bumper. If not, corner fridges have to be removed for even routine maintenance, which is a pain. But on the plus side, corner fridges are usually more protected from the elements, so when you do get at it, you usually find that it is in decent condition. It is also a fair bet that because corner fridges are so hard to get at, they don't get routine maintenance, so there is a better chance that the fix will be straightforward.
What to do if you can't fix it yourself?
If you can't fix it yourself, then you will have to get it fixed professionally. The good news is that these fridges are not specific to Hymer, are very common in thousands of caravans and motorhomes, and can be fixed by any competent caravan engineer. You can either book it in at your local caravan place, or book a mobile caravan engineer to come to you. Of all the things that go wrong with caravans and motorhomes, this is one of the commonest. Unfortunately as with all things mechanical and dealers, you have to make sure they do an honest job. But by reading this article you should at least now be able to sound as though you know what you are talking about and get decent service.
Recommended suppliers
For reliable repairs and advice - North Cotswold Motorhome Services in Stratford on Avon - they are Classic Hymer specialists.
For spare parts and good advice - Swordcrown Caravans and Motorhomes.
These are our two favourite suppliers, but by no means the only ones - if you have a favourite that you have used yourself and can recommend, then please let us know.
Old wives tales ...
If you ask online for help with a fridge, you will always get at least 2 answers. 1. Take it out and shake it up and 2. It must be level.
If the fridge is working on 220v, then you do not - must NOT - be tempted to take it out and shake it or rotate it. You could ruin the fridge. There is another blog on here about the specific circumstances you can do this.
As for being level - this is far less important than you would think. The manufacturer tolerance is 5 degrees, which doesn't sound like a lot, but is probably no more than you would be comfortable with in the van. If the fridge used to work OK, it is highly unlikely that it has suddenly developed an allergy to slopes.
Any more questions just ask on our Facebook group for recommendations and advice.
https://www.facebook.com/groups/297054424534823
Here is the Youtube video referred to above
https://www.youtube.com/watch?v=rBxt2BG7JbE
