Should I Replace My 20 Year Old Air Conditioner?
The life expectancy of a central air conditioner is about 20 years. Many factors go into determining when you should replace your existing system with a new one, including the size and efficiency rating of the unit, how well it has been installed and maintained over its lifetime, how old the ductwork in your home is, whether or not your house requires zoning (multiple thermostats) to control different areas/rooms in the house individually, etc.
I would recommend having an HVAC contractor come out for an inspection ($100-$200). They will be able to let you know what kind of demands your A/C units are under by looking at things like insulation quality in your attic and crawl space, the age of the ductwork in your home, how much insulation is wrapped around the ductwork within the ceiling, etc.
In general, if the contractor feels that the existing A/C units are still up to par with current building regulations and can be further repaired efficiently (at a low cost), they should last another 5-8 years. If, however, it looks like you will need all new systems or even multiple systems, it may be time for a replacement sooner than later before your energy bills go through the roof.
If you have a zoning system, the contractor should tell you what kind of life expectancy your ductwork has as well. If you have had repair work done to the ductwork over the years, this will cause premature wear and tear on the ducts themselves, affecting how well they operate and how long they last.
Have the contractor inspect your heating system if it is in a separate zone. If you have had multiple repairs or replacements to your zone system, it may be more cost-efficient to replace the entire area than to repair and replace components on the zone continually.
Replacing a central air conditioning unit can cost about $3,500-$8,000 for two 13-seer teams and a 2,200 sq ft home installation. The extra expense comes from requiring a new thermostat and running new wiring from the breaker panel to the outside A/C unit(s). Also, keep in mind that if your existing equipment is not up to code (efficiency-wise), there may be rebates available to help offset the costs of purchasing and installing more efficient systems!