I have a 3 year old Bryant air handler model FA4CNF048 and serial number 2109A84797 that has a R22 TXV installed from the factory. My contractor says he will have to change the TXV to R410 and then extract the old R22 oil and then he will be able to install a new 4 ton 14 seer R410 condensing unit outside. He was not sure if he should replace the coil in the air handler or not. He says he will check with the factory. What suggestion do you have? My 12 year old compressor died the other day and needs to be replaced.