Faulty turbo ?

[Focusladmk2]

 

Hi guys 

 

I currently have a mk2 Ford focus 2 litre tdci 

 

The turbo.has always been noisy/whistle is loud and clear and hasn't bothered me although im not sure if this is an issue however an issue happens when the weather is humid and warm where my turbo doesn't kick in, power is not good at all and temperature gauge rises. The car was plugged in last year and came up with fan didnt.kick in and since has been ok even though I didn't change anything, until today when we have had very warm humid weather. I sometimes here my fan kick in could it be faulty? Or am.i.not hearing the fan and the turbo isn't getting cool air. 

 Anybody else had this issue thanks