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Hi, I have a Liebherr CNes 4056 Index 21c/ 001 Service number 9989186-03.
I’ve spent far to long meddling with this problem, but I don’t like to admit defeat.
I’ve fitted a new freezer evap sensor already as this seems to be a common problem. I have also very carefully regassed with 46g of R600a using proper vacuum pump, scales and gauges.
Machine starts and compressor warms, but condensor tubing doesn’t seem to warm very far. The suction pipe cools rapidly on start up but gradually warms to around ambient. Accessing the service menu, the freezer evap sensor quickly records below -22c, freezer air temp -6 or so. Occasionally the freezer evap will hit -25c and the fan will start cooling the freezer compartment down to -18c.
Meanwhile the fridge evap sensor reads -6 or -7c but the air sensor only drops slowly from ambient temp. However the fridge display temp on the door seems to have a mind of its own and quickly records 5c, this activates the relay and the fridge stops cooling. The fridge never reactivtes and the display continues to show 5c when in fact the fridge air sensor and eventually the fridge evap sensor read ambient, which is +18 at the moment.
I’m beginning to suspect pcb module, but as they are quite expensive I would really appreciate a sharing of ideas and experience.
Thank you.
Re: Liebherr CNes 4056 – fridge not cooling
Why did you need to Regas the system?
The fault you have sounds like the the refrigerant system is blocked if the condenser at the back is not warming evenly.
When it does not cut back in is the compressor hot or cold?
If is hot.
You may have a blockage in the refrigerant system and if it builds up to much pressure the compressor will not be able to start up.
It may also be overcharged with refrigerant as if you recharge an R600a system that has not had a leak you need to Deduct 10{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of the original weight of gas as you will have 10{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of gas remaining in the compressor oil so you will be pumping liquid refrigerant around the system.
If it is low on refrigerant it will run continuous and take a long time to cut out .
If the compressor is cold then it will most likely be a faulty fridge evaporator sensor.
It is unlikely to be a PCB fault as there PCB’s are normally reliable.
Bob
Re: Liebherr CNes 4056 – fridge not cooling
Thanks for your quick response. I didn’t make allowance for gas remaining in the compressor oil, so it may be slightly overcharged. The compressor runs hot, and continues to cool the frezer, it’s the solenoid that once closed to the fridge evaporator section, never opens again regardless of what the sensors indicate.
It’s the mismatch between what the sensors read and the value displayed on the door that puzzles me.
Re: Liebherr CNes 4056 – fridge not cooling
It may have a blockage in the capillary tubes on the changeover valve to the fridge.
Or the change over valve may be faulty.
The freezer still runs as the fridge sensor is not getting cold enough to turn the fridge freezer off.
BobRe: Liebherr CNes 4056 – fridge not cooling
I’m also confused as to why this was recharged. That would be the last thing to look at on this appliance.
A blockage does seem likely as does a faulty valve, although they are normally very reliable.
The valve can be checked via the electronics.
Are you in the trade KRD?Re: Liebherr CNes 4056 – fridge not cooling
I’m an enthusiastic amateur I’m afraid.
I regassed the fridge to eliminate the possibility of a leak somewhere. I left the system on full vacuum overnight without any loss, so I believe that the system is gas tight.
The fact that the compressor is running hot, but the condensor is not warming across its full width does, now that you point it out, suggest a restriction.
As there are two capillary tubes, one for fridge and one for freezer, and that the symtoms are the same whichever capillary is in use, it is perhaps unlikely that both are blocked.
The solenoid valve can be heard to click when required, but could still be the source of the problem. The type fitted to this appliance has the coil around the outlet from the drier where it joins the two capillary tubes. The service manual I have seen, has a different type where the tubes run alongside the coil with two permanent magnets.
Is this an improved version? It would certainly mean that the coil could be changed without breaking into the system.
I can’t see any way of working with the valve I have in situ. Is there a way to diagnose a sticky or blocked valve?
Thanks for your help, it really is appreciated.Re: Liebherr CNes 4056 – fridge not cooling
hello,if you have a manual, its more than likely that the image you have for the valve is a generic one.
if you can hear the valve click over, then it’s normal to assume that the valve is good.
one of the purposes of the condenser grill is to dissipate the heat in the refrigerant and so it will be warmer at the point of entry of the refrigerant and progressively getting cooler as you work down and across.
if you’re thinking that the valve isn’t re opening at the correct time, then the problem is likely to be with the control of the valve, ie pcb or sensor. it maybe worth having a good look at the manual and seeing which sensor does what. which sensor changes the valve over. the air sensor and the evap sensor have different functions.
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