Air conditioner problems
Are you getting ANY cool air coming out of your vents or condensation drainage from the A/C drain pipe by your inside A/C unit?  A good rule of thumb I've used for residential A/C is to have about a 15-20 degree drop between room temperature and air coming from the A/C.  

A few suggestions to check before calling an trustworthy A/C repair service person:


Check to make sure you don't have a utility mizer device hooked up to your A/C that cycles the power based on a signal from your utility company.  If you do, you can contact them to make sure you don't have a problem that's causing the outside unit to cut in and out based on a faulty signal from your electric utility.
Check/change your inside air filter to make sure it's not blocked with dust/debris that's limiting airflow.
Check your outside unit to make sure the coils are clean and aren't being blocked.  If your coils look quite dusty/dirty, take a hose and spray out the dust and dirt.  DO NOT use a pressure washer as that puts too much force onto the aluminum fins and will cause them to bend and become less efficient in transferring heat away.


But, as others have suggested based on your comment about the outside compressor turning on and off every 3-5 minutes or so, it sounds like something that needs a professional to look at as the most likely scenario would be a coolant leak, which requires a professional to diagnose and repair.