There are many reasons why you should upgrade your cooling system before it completely fails, but the main reason is that it will most likely fail when you need it the most and then you are making a decision based on who can get the job done the quickest. If it is 90 degrees and humid, you really do not have time to research what may be the best unit or which installer is the most qualified. It is not uncommon that when the weather gets extreme, most contractors start to get a backlog and require about a week or more to get you on their schedule to install a new unit. The next fastest option may be to do a compressor change-out, but is it really wise to spend 1/3 of the cost of a new unit to repair your 15 year old unit; probably not. Again, you are making a decision based on how fast you can get your cooling back whereas RJ Kuhn in Oswego, IL. believes that you should be basing it on maximizing the value of your dollar.
Another important reason to consider replacing your old unit prior to failure is for energy efficiency. Units manufactured today (2015) are required to have a minimal efficiency rating of 13.0 Seasonal Energy Efficiency Ratio (SEER). Units manufactured 15 years ago only had a requirement of being a 10.0 SEER which would make a new unit 30% more efficient then your old unit. As a rule, every time you increase SEER by a whole number, you decrease electric consumption by 10%. Now 13.0 SEER is the minimal efficiency rating established by the US government for the northern portion of the country, but efficiencies on air cooled units can get over 18.0 SEER and still be reasonably priced.
Comfort can be another factor when considering replacement. Most of the older units are only single stage, they provide either 100% of capacity (on) or 0% capacity (off). The weather can be anything but consistent, we may experience an 82 degree day with 85% relative humidity or a 95 degree day with 70% relative humidity; either day we would want to run our cooling systems. However, on the 82 degree day with high humidity, we would not require our unit to provide 100% of its output to cool the home. In reality, a unit that could produce only 50% of its capacity would allow for a longer run time which would not only operate more efficiently, it would also do a better job of dehumidifying since it would have a longer run time. Almost every manufacturer offers a two stage unit, many even offer an inverter driven compressor which can provide between 30% up to 100% of capacity and everything in-between. Ask the professionals at RJ Kuhn in Oswego, IL. to help you to determine which is best for you.
Noise levels may not be a deciding factor when considering changing out your old unit, but it will help support your decision to do it now rather than later. Although you may be operating your cooling system, you will most likely want to relax outdoors whether it may be by your pool or to enjoy your gardens. Nothing can ruin a peaceful day outdoors as the noise emitted by an old condensing unit rumbling through its cycles. Most of the newer units utilize a scroll compressor which is inherently quieter than the old reciprocating style; so much that customers tell us that after they install a new unit, the only noise they hear is coming from their neighbors unit which is usually 100′ away while they are standing next to their own unit.