Are you a technician doing some air conditioning troubleshooting on a totally dead unit? Is it a nice hot summer day? Did you just finish a service call 20 minutes ago where you were sweating buckets wriggling around in somebody's steam-kettle attic? If you're done with your diet soda, grab your tools, crank up the can-do attitude, and let's go troubleshoot this air conditioner.
This unit's acting dead, so check the breaker, check the disconnect and fuses, and check to make sure you have correct power supplied to the unit. If the breaker is tripped and/or a fuse is blown, check the unit for grounds or shorts.