Is this for your personal residence or a rental unit?
This is my personal residence and not a rental property.
There is no deduction for your new central air conditioning unit under home remodeling. You may be eligible for an energy efficient tax credit if the new unit meets the requirements to be energy efficient. This would be entered in Form 5695.
To enter the air conditioning unit:
Use Form 5695 to figure and take their residential energy credits.
From @Opus17
When you are on the energy efficient credit section, the first screen will only ask you about alternative energy sources, such as solar and geothermal power. Click next or continue, and the second screen will ask about insulation, air conditioning and the furnace. The air-conditioning and the furnace are entered on separate lines. The air conditioner is eligible for up to $300, and I believe the furnace is only eligible for up to $150. The credit is 10% of the amount of the appliance.