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Hi,

a problem with a 2 year old (just out of warranty) Thetford fridge - manual control model (N80, I think)

Only use it on gas - was working perfectly last season. Went to use it for the first time this weekend and it lit almost at once, and remained lit.

The first thing I noticed was the temperature indicator didn't go into the green after a few seconds (as should be the case)  Instead, it moved up *very*  slowly to just below the green section - and remained there all weekend.

When the fridge is turned off the inicator jumps up into the green portion (where it should be while running) before rapidly sinking down again to the 'gas unlit' position.

The fridge is working, the ice box is freezing, and the interior of the fridge is cold - but not as cold as normal.

Adjusting the gas supply knob doesn't make much difference - I'm assuming a partially blocked burner? - allowing the fridge to run as if it was turned down, even when it's on max?

Does this diagnosis sound correct? - and, if so, is it a fridge out job to gain access to the burner assembly?

I've taken the rear vent off (all clean) and can see what I assume is the burner and exhaust - but see no way of working on it with the fridge in-situ.

OTOH it could be a completely different problem like a thermocouple - any advice as to the most likely cause of it suddenly not working properly after being laid up?

Thanks

Hi the indicator is just to tell you the gas is lit some go up higher than others & i dont know why.

The fridge needs to be pulled forward about 6 to 10 inches so that you can comfortably get your hands in to work on it, the burner is at the bottom of the flue pipe, you gain acces to it by removing the 8 mm bolts, which are really screws with bolt heads on them then removing the square box cover.

You then unscrew the gas pipe, the jet is a small cup shaped plate just sitting in the hole, sometimes it stays on the end of the gas pipe when you remove it, but more often than not it will stay in the burner nozzle, so you will have to undo the burner retaining screw then remove the burner to push out the jet.

Keith.

P.S remember to fit furniture protector plates inside the van so that the burrs caused by the fridge retaining screws dont scratch the furniture, or worse, rip the edges off,  the plates can be made by opening out tin cans then making them L shaped, you then shove them into the gaps between fridge & cupboards & tape the 4 pieces to the furniture in line with the 4 screws.

Quote: Originally posted by dionea on 04/5/2009

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Hi the indicator is just to tell you the gas is lit some go up higher than others & i dont know why.

The fridge needs to be pulled forward about 6 to 10 inches so that you can comfortably get your hands in to work on it, the burner is at the bottom of the flue pipe, you gain acces to it by removing the 8 mm bolts, which are really screws with bolt heads on them then removing the square box cover.

You then unscrew the gas pipe, the jet is a small cup shaped plate just sitting in the hole, sometimes it stays on the end of the gas pipe when you remove it, but more often than not it will stay in the burner nozzle, so you will have to undo the burner retaining screw then remove the burner to push out the jet.

Keith.

P.S remember to fit furniture protector plates inside the van so that the burrs caused by the fridge retaining screws dont scratch the furniture, or worse, rip the edges off,  the plates can be made by opening out tin cans then making them L shaped, you then shove them into the gaps between fridge & cupboards & tape the 4 pieces to the furniture in line with the 4 screws.

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Thanks for your info - the indicator normally goes well into the green, now it sits below the green - even after hours of operation.

I've just discovered that if I turn the power source selection switch to any other setting (with no 12 or 230 volt supply connected)  or even turn it to the  'off'' position  - and keep the gas control knob held in to avoid the thermocouple activating - then the gas keeps burning and the indicator immediately jumps to the correct position, well into the green.

As soon as I turn the selector switch back to the 'gas' setting the indicator again drops back to below the green segment.

Does this suggest a faulty thermocouple, rather than a partially blocked burner? - if so, how easy are the thermocouples to swap?

Thanks

I dont know what the guarantee period is.

Yes if you hold the knob in you will bypass the thermocouple & it will light in any position you are right there, but the thermocouple only holds the junkers valve open allowing gas to pass through the regulator, so it works or it doesnt, it in no way regulates the temp, that is done by the gas valve.

I cannot say whether a faulty valve will only allow a percentage of gas through but i suppose its possible.

Spiders are a major problem with burner units, they like to make their nests in the burners & even the flue, if theres a nest in there the gasses will fill up the tube then come out at the burner end, this could result in a diminished flame so causing the warmer temp.

Keith

Quote: Originally posted by dionea on 04/5/2009

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I dont know what the guarantee period is<<<

I believe it's 2 years - but I'll be checking with Thetford in the morning

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Yes if you hold the knob in you will bypass the thermocouple & it will light in any position you are right there, but the thermocouple only holds the junkers valve open allowing gas to pass through the regulator, so it works or it doesnt, it in no way regulates the temp, that is done by the gas valve.<<<

Thanks - I'm beginning to suspect the gas valve -  it definitely works properly (needle into the green area) when used on gas by holding in the thermocouple and switching to other power positions - so, presumably, that means that any gas restriction is the fault of the gas switch (when set to 'gas'), rather than a burner obstruction?

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I cannot say whether a faulty valve will only allow a percentage of gas through but i suppose its possible.

Spiders are a major problem with burner units, they like to make their nests in the burners & even the flue, if theres a nest in there the gasses will fill up the tube then come out at the burner end, this could result in a diminished flame so causing the warmer temp. <<<<

As above - but I'll certainly check the jet before proceeding further, once again, many thanks for your advice.

regards