fridge/freezer noisy fan

Hi there. I have a noisy fan on my fridge/freezer. When I open the fridge door the fan slows and then stops with quite a lot of noise. With the door closed, the fridge is still noisy, so I’m assuming it must be a fan connected to the fridge operation because it only shuts off when I open the fridge door.

Is it a fairly easy DIY replacement, or would I need an engineer to fix it?

Thanks, Les Greenwood