We noticed ice creams were not as hard as usual in March, getting softer and softer as time went on, the bag of ice was turning into a solid lump, which i just thought was due to it being from last year and not much ice being used over winter, so it was defrosting a little each time i had the door open to re-load it with food)
The final indicator something was wrong was when we woke up 2 days ago to the beeping of the defrosting food alarm, it was showing a temp of -1 in the freezer (in normal operation it just shows the set temp of the compartment selected, and a tiny triangle points up or down to show if it is below or above the set temp)
I just found out this unit has onboard diagnostics (open fridge door, hold fast freeze button, close fridge door then release FF button) it will do a self diagnostic and show up any fault codes on the lcd, but we get a 00 at the end of the test which means all electronic items are working,
There is also a manual test accessible by pressing the defrost food alarm silence button 5 times after opening the fridge door when it's doing the self test, then you can select the main components to operate manually.... air flap motor open and close, run the circulation fan, defrost heater, gutter heater and so on, all are working fine.... sorry for the waffle, just thought i'd put how to get into the test mode as i never knew it had one in the 9 years we've owned it, and someone else might have the same model fridge freezer and want to play :)
I also found out it has more features than i knew about, like showing the max temp' the freezer rose to during a power cut when the power comes back on!! bloody handy that as we've had power cuts whilst out of unknown duration and never thought about the food in the freezer defrosting then re-freezing.
Anyway, i am thinking the problem is an absolutely tiny leak somewhere in the cooling circuit, The compressor is running almost all the time and is running very hot, the condenser is hardly getting warm at all and the evaporator forms frost only on the upper quarter of it, this unit has a single evaporator in the freezer and blows cold air from the freezer compartment into the fridge (i think most modern fridge freezers do that nowadays)
it used to make the usual whooshing and groaning sounds in the pipe work after the compressor shut off and the high and low pressure sides equalized, but it's making them all the time the compressor is running now as well.
I know there are many other things in a cooling circuit that could cause the lack of cooling power (blockage, dryer contaminated, higher than designed for ambient temps etc) but the ambient temp where the fridge lives has always been and still is around 20 degrees C, it's not been tilted for more than 5 years, just pulled out once a year to hoover the floor and the condenser fins, last done 8 months ago... and condenser fins are still clear.
The door seals are fine, tested with a piece of paper, it grips it all round, and no signs that a rodent has chewed a hole into the freezer compartment :) And the 'common fault' with this model of the air ducting at the back of the freezer building up ice until the fan blades hit it has not happened for a couple of months.
I know i should just get a fridge engineer out to check the pressure and re-gas it if needed, but would such a small leak be detectable if that is the problem? Money is extremely tight, and i'm stuck weighing up a possible fix that fails after another couple of months, or putting the cost of that possible failed fix towards a new fridge freezer.