Hi thanks Colin,
the freezer fan should run all the time the compressor is running.
You can try replacing the thermistor as that can cause this problem because it tells the main control board what to do;-)
Also it's an inexpensive part.
If that doesn't do the trick, the next thing would be the main control board:-( That is a bit pricey.
The best place to get that thermistor would be: www.ransomspares.co.uk
I would call them to order this part so they ship it out today;-)
Please call: 0844(###) ###-####a href="http://www.ransomspares.co.uk/" target="_blank">Home » Parts » Kitchen Spares » Fridges & Freezers » Bosch
In any case, I will stick with you until this is complete.
Please rate my service kindly.
Also it is the only way I am credited for my time and expertise with you.
Once you rate, I will be notified and will add your question to my priority list so you can reach me anytime until this problem is solved.
Then you can reach me by simply replying to this message anytime.
Thank you and have a great day Colin!