Hot weather is here, and if you haven't yet had to turn on your air conditioner, you'd better take a look at it first to ensure it will provide the cool air you want. After several months of being turned off, your air conditioner can be a little on the sleepy side, and it's up to you to get it up to speed.
The Simple Stuff
Change the filter before anything else. That one piece can make your air conditioner strain more and deliver less cool air if it (the filter) isn't in good shape. Even if you put a clean filter in before turning the system off for the winter, change it again to ensure any dust that's gathered on the filter won't interfere with the unit's operation.
No matter what type of air conditioner you have, look at all exterior parts inside and outside your home. Clear away brush and leaves; make sure there are no signs of pests trying to live in the outdoor compressor, for example.
Also look for dents, cracks, missing, and bent parts. Have those inspected and possibly replaced by an air conditioning repair company.
The Not-So-Simple Stuff
Look at the drainage hoses and insulation around the larger pipe in a central unit. There should be no leaks, holes, torn areas, or even frayed spots. Those all need to be fixed before you turn the unit on. Also, clean the sides and top of the coil; there are several crevices, as you can see, so while this is a straightforward job, it can take some time.
Another option is to hire an air conditioning repair company to check out the entire unit. This is likely the better option if you've just moved into the home and aren't familiar with the unit, or if you've never before tried inspecting the type of system you have.