Whirlpool Side-by-Side shows Error Code CF. What are my Options?

The performance of our whirlpool side-by-side freezer (Model No 8586 151 01011) has been degrading slowly over the last few weeks. In the end we repeatedly got temperature alarms and had to turn on the superfrost feature to get rid of them. Finally a CF error code is flashing.
A first check revealed that the condensor was completely blocked with dust, which explains the poor performance issue. The condensor is free of dust now, but the problem still persists. After a minute or so, the CF alarm is triggered.
I have already checked the condensor fan. It is running quite fast and blows a reasonable amount of air. The compressor seems to operate, too. It is warm and vibrating, yet the condensor is rather cold.
Food stays frozen, but the cooling compartment is not very cold. Obviously the compressor doesn't generate enough cooling power.

What does the error code CF mean (for other models it is 'condensor fan', but is this true for my model, too - could it for example also mean 'compressor fault' ?)
Since the compressor must have been operating continuously over the last few weeks, could it be that it was overheated and possibly has been damaged?
How can I check this?
What other causes should I consider?