Some reasons to have your AC properly maintained are:

• ✔
  A dirty outdoor cooling coil can cause refrigerant pressure to run too high and start to burn
• ✔
  A plugged filter can cause the indoor cooling coil to freeze up
• ✔
  A bad contactor could draw more amperage and run up your electric cooling bill
• ✔
  Bad wire connections can break loose and cause a short and fry some expensive components
• ✔
  An unbalanced refrigerant charge can easily shorten the life of the compressor
• ✔
  Proper charging procedures will extend the life of your very important air conditioning
• ✔
  Fan speed on the indoor cooling unit can also offset the charging process