How to prevent sparrows from nesting under roof air conditioner unit?

[Sunny18]

 

We found that birds had been nesting both in the unit and in the box underneath the unit which they were accessing under a tin platform which had a small gap in it. Although the A/C technician had sealed the A/C unit,, the birds still access the roof via the corrugated roofing as well. What should I do? 

Some people had suggested installing gutter guards to prevent birds from landing on the  roof. Please advise, thank you