Finding faults in motorhomes can sometimes be a nightmare, especially if there happens to be more than one fault affecting the equipment in question.
I recently had a vehicle in the workshop with a motorhome fridge that wouldn’t ignite the gas.
On removal of the fridge (that lower vent was too high to access the burner in situ), it was soon established that there was no spark getting to the burner electrode.
A quick check proved the piezo device was working. A broken ignition lead was found, so I ordered a new one.
Thankfully, the customer in this case was local to me, so bringing the vehicle back was not going to be a problem.
With the new ignition lead acquired, the fridge was removed again for fitting. The burner, jet and flue were cleaned while the unit was out.
Once refitted, the fridge malfunctions continued – it would now ignite, but go out immediately about four times, then not light at all, even while the valve was pressed in. If it was left for a few minutes, it would light but go out again numerous times, then not light at all.
Removing the fridge again
So I removed the fridge for the third time, and established that there was a good gas supply. But by now, it was head-scratching time.
Disconnecting the outlet of the gas valve showed that it would initially supply gas, but fade off after a few seconds. So a new gas valve was ordered, and the fridge refitted for safety until the valve arrived.
The following week I had the new gas valve and fitted it. Great, the fridge would now light and stay lit as long as you held the valve in – but as soon as I released the valve, it went out. This is typical of a failed thermocouple, so I tested that – and it worked perfectly.
The thermocouple is a very simple device. The hot end contains two dissimilar metals joined together; when heated, this produces a low voltage that is just enough to energise a tiny electromagnet in the gas valve to hold it open.
On this type of fridge, the thermocouple circuit goes through a pair of contacts on the energy selector switch that are only closed when gas is selected. Turn the selector to 12V, for example, and the thermocouple circuit is broken, and the gas valve closes.
Over time, the contacts in the energy selector switch get dirty or corroded, introducing an electrical resistance into the thermocouple circuit and reducing the voltage to the electromagnet. Then the gas valve won’t stay open. A new energy selector finally fixed the problem.
Without ignition in the first place, the gas valve fault wouldn’t show up. Only once the ignition and gas valve had been fixed did the energy selector fault make its presence known.
Of course, if you find you’re in need of more cooling space in your ‘van, something you could consider is a cool box. Take a look at our guide to the best cool box for a campervan to find our favourite options if you’re after some inspiration.
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