Before you call the repair man, google google google.
This very much sounds like the problem we have, it is unlikely that the condenser is buggered. We have a side by side fridge freezer and it started doing what yours did.
Here is a list of things to try
- Hoover out behind it, look to see where the heat exchager is - it will be metal pipework with some sort of fins on it (a bit like the carb in the car), they get dusted up and then can't dissipate the heat which in turns takes the heat from inside the freezer.
- Defrost it - you will need to leave it off for at LEAST 24 hours, we thought we had defrosted it and there was a HUGE glacier around what we found to be the defrost heater (this is what keeps the thing frost free).
Check that the fans are working
There should be a fan near the motor/compressor thing - see if that is working.
There will also be a fan in the back of the freezer somewhere that fans the cold air through to the fridge - that could be getting stuck (this thing is NOISY so could explain the noise - if the noise stops wen you open freezer, it could well be this).
IF you do manage to take the back off and find ice around the defrost heater, it could be one of three things - the defrost sensor (small thermostat in back of freezer - they cost about a tenner), the defrost timer - they cost about £40 and look relatively easy to replace. Or the defrost element itself - if its that, id say you're buggered because they are rivetted in place and you would have to tke the freezing element out - my DP told me in no uncertain terms i wasn't to be messing with that (im a big gun ho - have screw driveer will fix), you do have to be careful because the refrigerant gasses are highly flammable.
If there are problems with the defrost system, you do tend to notice frost build up in the freezer. The reason the temp on the fridge goes up is because the fan cant push the cold air in, it gets stuck.
Could be your refrigerant levels are low - get a new fridge freezer as it would cost as much as a cheap one to replace.
Cleaning the heat exchanger (i think thats what its called) and defrosting our bastard machine fridge freezer worked, FOR A FEW MONTHS, the problem recurred and i had to do it again, if it happens again i will replace the sensor i mentioned above, if that doesnt work - the bloody things going!