Air conditioner
As spring turns into summer and temperatures rise outside, so do the use of air conditioners. With just basic regular maintenance, building occupants won’t be caught off guard and subjected to sweltering heat.
Change the filter regularly—every three months is considered standard. But the more the air conditioner is used, the more frequently the filter should be changed.
Have a qualified licensed technician go through the system and do basic overall service. They can change the filter, clear any of the condensation drains, and clean the coils, both interior and exterior if you have a split system. They can clear out the dust within the air return and clean the blower or change any worn gaskets. This should be done once a year on systems in good condition, but as the unit gets older it may need to be done twice a year.
If the ducts haven’t been cleaned in a while, you should consider having them cleaned. A property inspector will always comment on a poorly maintained system, so it behooves you to stay on top of it.
Other Parts/Systems of the Building
Bathroom vents get clogged with lint and dust which could affect use, allowing steam to linger in unwanted spaces.
Some buildings are equipped with attic fans—some on a switch and some thermostatically controlled. Have a technician check the thermostat setting to ensure it operates during summer to help remove that excessive heat.
If you want to be thorough and save energy, you could check the doors and windows to make sure the seals are in good repair. If weatherstripping is missing, such as around doors and older windows, consider improvements to ensure efficient use of your system.
Enjoy a 
summer!