Noisy Whirlpool Side-by-side

[jez p]

Hi - have a Whirlpool side-by-side that is making a lot of noise. Sounds like a fan is running nearly all the time. Noise is louder if the freezer door is opened suggesting the fan or whatever is that side, but it cuts out when the fridge door is open and starts up again when the fridge door is shut.  Have tried hoovering underneath as suggested in Whirlpool manual to clear accumulated dust.  There is some vibration I guess as the noise can changed sometimes by moving the appliance, but the fan thing keeps running.
Any ideas? Thanks

Model Number: 20RID4