Beko TL546APW Fridge running constantly.

I'm at my wits end with this fridge! It has started to run constantly (compressor NEVER stops) and ices up inside. I assumed it was a faulty thermostat and fitted a replacement - no difference! The capillary is 1200mm and disappears into a long sleeve within the machine so no way to check that it's correctly sited. To make sure I hadn't received a faulty replacement I tried another thermostat I had handy with a shorter capillary. This time I simply taped the capillary to the inside of the back wall and tried that - again, no difference - the compressor never stops. I left it for a few weeks and the ice built up so that eventually my temporary thermostat capillary became frozen in the centre of a huge block of ice. Even after that however, the compressor still refuses to stop!! The fridge wiring is correct (nothing's been touched from new) and the machine turns off when the thermostat knob is turned to off.

This fridge is a simple design - auto defrost controlled entirely by the Ranco K59 thermostat - no heater in the condenser, no separate stat, thermistor or PCB of any kind.

My first thought was that there's something amiss down in the sleeve for the capillary so the thermostat isn't sensing the temperature but then why would my 'other' thermostat not cut out with its capillary frozen in a block of ice?

As far as I can see the compressor is working normally but just not receiving a signal from the stat to cut out but surely two replacement stats can't be faulty?

Could there be some anomaly in the coolant circuit causing a blockage or air bubble at the point where the thermostat capillary senses the temperature? I'm almost tempted to turn the machine upside down then back again to see if that redistributes the coolant - would that do more harm than good?

Can anyone throw any light on this weird machine?

If you remove live from the stat, does the compressor cut out? If yes then stat is faulty, or bulb is sited incorrectly.

Yes, turning the thermostat knob fully anticlockwise cuts out the compressor. I'm suspecting a coolant problem at the point where the bub is sited. Could I replace the thermostat with an air sensing one? Someone suggested this on a different threadhttps://www.amazon.co.uk/THERMOSTAT-...ct_top?ie=UTF8 Reviews are mixed though - anyone know of a more accurate air sensing thermostat?

Turn the unit off for a 24 hour defrost with the door open.
The more ice that forms on the evaporator the less cooling you will get as ice is a good insulator against heat transference
See how it operates after before you start doing any other mods

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Originally Posted by frank

Turn the unit off for a 24 hour defrost with the door open.
The more ice that forms on the evaporator the less cooling you will get as ice is a good insulator against heat transference
See how it operates after before you start doing any other mods

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I think I've tried this before (the fridge has been faulty for nearly a year!) but can have another go. The evaporator itself is completely hidden - just the plain white plastic walls of the cabinet - and the thermostat probe disappears down a (long!) sleeve. Nothing is directly accessible unless of course I cut into the foam insulation covering the outside of the back.

I did wonder about trying the serious step of turning the fridge upside down for a day then back upright for another couple of days to see if it clears any blockage. Is that likely to do more harm than good? Is there any way that a quantity of oil could become trapped in the system leading to incomplete cooling of the evaporator? If the evaporator is not cooling properly at the point where the thermostat bulb senses the temperature would that account for this strange behaviour?

Turning the fridge upside down will allow the compressor motor to fall off of the mounting springs, not a good thing really.

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Thermostats for domestic fridges tend to be two types.
One type measures the air temp of the inside of the fridge the other measures the temp of the evaporator.

Both types then have lots of different variations within their type.

If you do not have the like for like replacement then it will cause problems.

The biggest issue I found from this type of temp probe (sensing probe) is it doesn't always push in as far as the old one was and therefore the probe does not read the correct temp.

This tends to be because of ice build up.

I always Mark the old sensing tube and measure it against the new to ensure the probe goes in the right distance.
You can't measure it now so I would turn it off for 48 hours, remove the probe and try to insert it back in all the way.

Don't turn it upside down, that is for a completely other type of fridge and will not help your fridge in the slightest.

Sometimes in the confusion of fitting the new stat people confuse the terminals (if there are three) if you have just two electrical terminals then ok but if there are three check the connections.

taz

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Originally Posted by Brian_UK

Turning the fridge upside down will allow the compressor motor to fall off of the mounting springs, not a good thing really.

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I was going to secure it but will try getting the probe further in first as Rob is suggesting.

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Originally Posted by Rob White

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Thermostats for domestic fridges tend to be two types.
One type measures the air temp of the inside of the fridge the other measures the temp of the evaporator.

Both types then have lots of different variations within their type.

If you do not have the like for like replacement then it will cause problems.

The biggest issue I found from this type of temp probe (sensing probe) is it doesn't always push in as far as the old one was and therefore the probe does not read the correct temp.

This tends to be because of ice build up.

I always Mark the old sensing tube and measure it against the new to ensure the probe goes in the right distance.
You can't measure it now so I would turn it off for 48 hours, remove the probe and try to insert it back in all the way.

Don't turn it upside down, that is for a completely other type of fridge and will not help your fridge in the slightest.

Sometimes in the confusion of fitting the new stat people confuse the terminals (if there are three) if you have just two electrical terminals then ok but if there are three check the connections.

taz

.

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It's possible that the probe isn't getting quite far enough although I have been quite fussy about easing it gently in until I could feel an obstruction.

I'm a bit frustrated with the evaporator being completely inaccessible. Is it possible that ice is building up behind the fridge wall or within the sleeve for the probe? That would seem unlikely because there is no way it can defrost to - unlike the fridge interior which has the drain. Everything seems to be encapsulated in foam insulation.

Is is at all feasible to dig out the foam insulation to access the evaporator then reinstate it with spray foam?

I'll try a 48 hour defrost with the probe out first then reinstall the probe as far as I can.

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Originally Posted by Coolguy

I was going to secure it but will try getting the probe further in first as Rob is suggesting.

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By motor I meant the motor beside the compressor shell. That's why they have the wine glass on the outside of the cardboard packing.

Ah - within the shell - got you! Right - will abandon that desperate measure. Thanks.

Possibly short of refrigerant as if the plate is not fully flooded the end where the probe is located will not be cold enough to trip stat.
Twas the case on mine.

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Originally Posted by Jeff Winsor

Possibly short of refrigerant as if the plate is not fully flooded the end where the probe is located will not be cold enough to trip stat.
Twas the case on mine.

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Sounds possible Jeff - did you get it repaired at reasonable cost?