Looks good, but an important reason for a 'computer' fan is to suck HOT air out (not push cool air in) from the electronics and compressor area (unless you have 2 fans)
You will need to have 2 separate areas, one allows the cooling air to be drawn into the fridge electronics etc, the other is the way out for the heated air.
Like the analogy of snorkel and exhaust pipe
To do this, put some very dense foam round the 'exhaust' area of the fridge, to form a 'tunnel' or 'funnel' to the timber box side, with the fan placed so it draws the hot air out of the fridge and pushes it through the (exhaust) hole/s in the box keeping it well away from the (snorkel) cooling air going into the fridge