I have a home in Florida built 12 years ago that has 4 HVAC zones. The condenser of one zone was replaced with a brand new one in February 2009. My service company is now recommending that I replace the air handler attached to that new condenser because, if it fails, I would have to replace BOTH components of that system due to the changeover from R-22 to 410A equipment mandated soon. Is this true and why? Also, what can I anticipate for the other three systems that are now working adequately?