Last summer the central AC in my home started freezing up. My furnace is 32 years old and the outdoor AC unit is 22 years old! So I'm looking to replace both. I've gotten a couple quotes from businesses I found off Google and was suprised at the price, it seems that labor is about half the overall cost. Anyone have experience, doing it yourself, good idea or bad idea? Seems that if you don't have it professionally installed it voids warranties. Any recommendations for a good company to do the job? Brands to target/avoid? Any advice would be appreciated. Thanks.