Time for another fridge thread

[tidewatcher]

I have a Thetford W97 three way fridge which has worked pretty well until recently. Well aware of the need to be level and have twin computer fans fitted to help the airflow. Recently in Spain temperatures reached the mid thirties and the fridge had a touch of the vapours. The freezer compartment remained ok with ice cubes not melting but the main fridge area was barely cool.

Having read as much as I can about this there seems to be some discussion about the auto defrost system and the sensor on the main fridge cooling fins. Can this be checked? Or is the fridge just outside it’s limits at the mid thirties. When we returned to more sensible temperatures of mid twenties then it eventually sorted itself out.

So am I expecting too much or is there a problem?

 

[trevskoda]

Think its normal for them, its an old out of date sys these days, better go for an all electric to be honest.

 

[wildebus]

I understand that once the exterior (to fridge) temps go above 30C, they are not able to cope that well? Also, counter-intuatively, as the exterior temp increases, people seem to have to turn the fridge down in terms of power level (so 2 bars from the 3 rather than going up to 4, for example).
got little experience with the 3-ways, but yours sounds it it working as well as can be expected.
Switch to compressor as Trev is saying would give you a much better performance but you would need a bit more battery maybe - but having said that, the high temps tend to go with sunny weather and if you have solar it could easily deliver within a couple of hours what a compressor fridge needs in a whole day.

 

[trevskoda]

I understand that once the exterior (to fridge) temps go above 30C, they are not able to cope that well? Also, counter-intuatively, as the exterior temp increases, people seem to have to turn the fridge down in terms of power level (so 2 bars from the 3 rather than going up to 4, for example).
got little experience with the 3-ways, but yours sounds it it working as well as can be expected.
Switch to compressor as Trev is saying would give you a much better performance but you would need a bit more battery maybe - but having said that, the high temps tend to go with sunny weather and if you have solar it could easily deliver within a couple of hours what a compressor fridge needs in a whole day.

It was you put me down this path which works very well, Thanks.

 

[Canalsman]

I have a Thetford fridge too, but a different model.

I have just returned from the south of France where the temperature was in the upper twenties and reached 32 degrees on one day.

The fridge performed well throughout. I have two fans drawing air out through the top vent and the vent is masked round the fans to ensure that no air can leak round the sides of the fans.

I am aware of the auto defrost cycle which I believe happens every 40 hours. I've no idea why this is necessary. I have a reminder on my phone to reset the fridge daily which I do by switching it off for 10 seconds then switching it on again.

This resets the timer and i suspect that auto switching to 12 volts when driving does the same.

The thermistor attached to the cooling fins inside the fridge can be moved to vary its performance. I unclipped it and moved it two fins to the left which I have found enables more sensitive control of the fridge.

From your description I think the fridge is not behaving as it should. More than likely the jet is blocked. I find I have to clean the jet every three or four months to maintain performance. My fridge is running 24/7.

I clean the jet when removed by squirting brake cleaner through the jet a few times. I then use an aerosol air duster to blow through the jet. This works a treat.

Don't introduce anything into the jet to try cleaning it mechanically. The jet WILL be damaged.

Replacement burner assemblies which includes the jet are available quite cheaply on eBay. I keep a spare on board just in case.

 

[tidewatcher]

I have a Thetford fridge too, but a different model.

I have just returned from the south of France where the temperature was in the upper twenties and reached 32 degrees on one day.

The fridge performed well throughout. I have two fans drawing air out through the top vent and the vent is masked round the fans to ensure that no air can leak round the sides of the fans.

I am aware of the auto defrost cycle which I believe happens every 40 hours. I've no idea why this is necessary. I have a reminder on my phone to reset the fridge daily which I do by switching it off for 10 seconds then switching it on again.

This resets the timer and i suspect that auto switching to 12 volts when driving does the same.

The thermistor attached to the cooling fins inside the fridge can be moved to vary its performance. I unclipped it and moved it two fins to the left which I have found enables more sensitive control of the fridge.

From your description I think the fridge is not behaving as it should. More than likely the jet is blocked. I find I have to clean the jet every three or four months to maintain performance. My fridge is running 24/7.

I clean the jet when removed by squirting brake cleaner through the jet a few times. I then use an aerosol air duster to blow through the jet. This works a treat.

Don't introduce anything into the jet to try cleaning it mechanically. The jet WILL be damaged.

Replacement burner assemblies which includes the jet are available quite cheaply on eBay. I keep a spare on board just in case.

Many thanks for that. The auto defrost is a bit of a mystery as it seems to turn off the fridge until defrosted. When in the top end of the fridges ability due to the temperature I wonder if after turning off it just struggles to reduce the temperature again. As I said the ice box maintained the ice cubes frozen but the fridge body was hardly cool. I will remove the fridge, it was fitted by a midget three armed conversion specialist and virtually inaccessible through the external vents, and clean the jet as you described. Trying to contact Thetford to ask questions is impossible and the agents only want to sell you a new fridge. Also while it is out of the van I will do the upending trick for twenty four hours. Thanks.

 

[TeamRienza]

I seem to recall in reading fridge threads down through the years that,
The fridge cannot react to external temperature changes. It simply has the ability to reduce the air temperature inside the fridge by a set range of temperatures dictated by the setting you select.
I also seem to recall that fridges (caravan & Motorhome) are manufactured to suit two climate ranges, simplistically one range for temperate European markets and another for where use is likely to be in permanently hotter climates.

If anyone can confirm these vague memories it may be helpful.

Davy

 

[Canalsman]

Many thanks for that. The auto defrost is a bit of a mystery as it seems to turn off the fridge until defrosted. When in the top end of the fridges ability due to the temperature I wonder if after turning off it just struggles to reduce the temperature again. As I said the ice box maintained the ice cubes frozen but the fridge body was hardly cool. I will remove the fridge, it was fitted by a midget three armed conversion specialist and virtually inaccessible through the external vents, and clean the jet as you described. Trying to contact Thetford to ask questions is impossible and the agents only want to sell you a new fridge. Also while it is out of the van I will do the upending trick for twenty four hours. Thanks.

Whilst it's out I suggest you fit a new burner given that the assembly cannot be reached externally.

Make sure, as I mentioned, that the fans are only drawing the warm air up from behind the fridge. If the fridge is not directly aligned with the upper and lower vents it is much less easy for the heat to be dissipated.

 

[Canalsman]

I seem to recall in reading fridge threads down through the years that,
The fridge cannot react to external temperature changes. It simply has the ability to reduce the air temperature inside the fridge by a set range of temperatures dictated by the setting you select.
I also seem to recall that fridges (caravan & Motorhome) are manufactured to suit two climate ranges, simplistically one range for temperate European markets and another for where use is likely to be in permanently hotter climates.

If anyone can confirm these vague memories it may be helpful.

Davy

I'm pretty sure you're right.

It's noticeable that motorhomes sold on European markets have much bigger external vents presumably to permit better heat dissipation.

 

[wildebus]

I'm pretty sure you're right.

It's noticeable that motorhomes sold on European markets have much bigger external vents presumably to permit better heat dissipation.

Is it down to the market, or the fridge make? The Dometic fridge vents appear to be twice the size of the Thetford ones. If vent size could be an issue, fitting a vent fan kit for some forced cooling could be a good idea. (probably a good idea regardless of vent size).

 

[Pudsey Bear]

Simple physics can help too, keep the door closed as much as possible, keep vents in the shade, also internal fans can help circulate the frigid air which tends to pool at the bottom this is why your salads sometimes freeze, and of course don't jam the fridge full as air needs to circulate.