I am having a problem with blown fuses,restaurant has a 100 amp box just for a/c units
But recently of the heat the fuses blown once all the a/v are on.
Last year we have the same units but we did not have any problems at all.

This is in a restaurant?

Call and electrician or HVAC guy right away.

I agree with Stan but you may be experiencing a "brownout" with lowered voltage in. In this case, if watts are the same, the amperage draw will go up. I would guess these are 240V or higher.

Any number of causes. One such cause is a momentary power glitch and no anti-short cycling timer.

No random delays on start up.

And LOTS of other things.