I know what you mean, there is like a million other  things Id rather spend my money on, And I really dont want some AC guy to come out and scare me into spendy repairs or a new system when my current system seems to be working fine.
@Zeeman: We have used Deerwood (I think) in the past and they did a good job for us. If your system is working fine, you can always do the simple things yourself, such as putting in a new air filter in your inside air inlet, and cleaning the outside condenser by spraying the fins with a garden hose. Also, you can make sure the outside unit does not have a buildup of leaves, weeds, etc, around it. More air movement = better cooling. I also turn off the breaker for my outside units, and spray the condenser fins with a cleaning spray, and then rinse once a year. Most folks might not be comfortable going to that step, but it is easy for me to do.
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