Opening up the PSU/SMPS

my psu fan is making a lot of noises which makes it a trouble some time using the system! i cannot replace the whole PSU (power supply unit) for a small fan.

my question is that can i open up my PSU and clean my fan?

i read somewhere that it's dangerous to open up the PSU!

I don't want to pay a tech. guy to do the job for me!