1 SMEG fridge/freezer cooling for 30 minutes - then stops cooling
Hi!
I recently purchased a used Smeg FAB32 Fridge/freezer with a cooling issue. The unit is only four years old so it's in great condition, apart from the fact that it’s only cold for 30-60 minutes. I was hoping it could be an easy fix but turns out it's a bit more challenging.
Symptoms
The compressor turns on when plugging in the unit and the temperature in both compartments starts to drop. There’s heat radiating from the condenser coils in the back and everything seems OK. The fridge reaches 6 deg C and the freezer -14 deg C. After 30-60 minutes the compressor slows down (still running but very slowly) and the temperature starts to rise in both compartments.
What I've done so far
I though it could be a leak so I emptied all the gas (R600a), added a service port, and pressurized the system with an air compressor to about 100 PSI. It held pressure for more than 8 hours and I've performed the dish soap bubble test on all the pipes around the compressor and on the evaporator coils in the freezer department. Couldn't find any leak. Checked with a leak detector as well.
I emptied the air, drew a vacuum and refilled the system with R600a. Still the same cooling issue.
I’m thinking it might be a sensor issue since the compressor is slowing down and acting like it reached the correct temperature. But there’s a digital display on the motherboard displaying the temperature and it’s showing that it’s too warm. I’m guessing it’s using the same temperature sensor for the display value and the logic in the motherboard or am I wrong?
Would be super grateful for any help or nudge in the right direction!
Hi @jonasscones ,
Having you tried placing appropriate thermometers in each compartment just to check that the displayed temps are as shown (within a degree anyway)?
Does the compressor then "restart" after a while and then temps go back down again or does the compressor finally stop and they continue to rise?
At what temp (fridge and freezer) do they start to go back down again if they do?
Looking at the parts list there are only three sensors. A temp sensor in each compartment and a defrost sensor with the evap unit You didn't state the full model number so the link was a guess as it has the same first 5 characters in the model number.
With most fridges that have a temp display the value is derived from the sensors' resistance value as its resistance is a known value for each temp value within its operating range. The sensors are actually NTC thermistors(Negative Temperature Co-efficient). As the temp goes up their resistance value goes down
jayeff さんによる
Hi @jayeff
Thank you for your reply!
Yes I've used an IR thermometer to check the temperatures. The actual temperatures are as shown on the display. The thermometer should be accurate within +-/2 deg C.
The compressor never stops running completely. But it's slows down (or at least it gets more silent) and then the temperature starts to rise. The evaporator fan stops completely when the temperature starts rising and never comes back on. Maybe this could be a sign of something?
They never drop in temperature again. Not unless I unplug and restart the system.
The exact model number is FAB32LPG5, I think the last four digits is the color code. And yes you are correct, there are two sensors in the freezer compartment and probably one in the fridge that I haven't found yet. One that's connected with the defrosting heater and one that's jammed in between the evaporator coils.
I truly appreciate the time your taking to help me out!
Jonas Lundin さんによる
@jonasscones
If the temp keeps rising then the sensors in the compartments should signal the control board that the it is too warm and it should restart the compressor and evaporator fan to drive them back down again.
This includes the defrost sensor. However the defrost sensor usually only comes into play during the defrost cycle and is used to end the cycle when its set temperature is reached normally around 10-12 C but it may be different in your case.
Perhaps it is a control board problem as it seems that it has to be "reset".
Have you looked at the control board for anything obviously wrong?
The evaporator fan stopping usually means that the set temps have been reached and the compressor is also stopped at the same time as there is no reason for it to continue operating until the temperature has started to rise above the set upper limit for either compartment
jayeff さんによる
Thank you @jayeff
I'll have a look at the control board ASAP and see if I can find anything. I'll see if I can measure the resistance of the sensors as well.
The unit has been on for 16 hours now and I'm getting an error code that I haven't seen before. "LL" for the freezer and "L" for the fridge. Couldn't find anything in the manual or online about it though
Jonas Lundin さんによる
@jonasscones
The only general SMEG refrigerator error codes that I found are LF and LP
LF means that the freezer is too warm and to reduce the freezer temp setting and LP means that the supply voltage is less than 170V and to wait until the correct supply voltage is restored for normal operation to occur again.
Have read a manual for a similar model (couldn't find one specific to yours) and it mentions having an "eco" mode which reduces power consumption (I'm thinking compressor) after 6 hours of operation. Can you turn the eco mode on and off as there should be an indicator light? Also turning on supercold deactivates it. This is for a FAB32LPG3 so maybe the same for your model.
Just trying to eliminate things ;-)
jayeff さんによる
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