I've read through their contract, @Jonathan G. is spot on about the freon. They only cover $10/lb for freon. This house I've had serviced three times in the last 5 years (and it needs it again), and freon (R22) is going up each year, I think $35/lb was the best price I was able to find last year, and it just keeps going up. It's possible that, since you can't shop around for your own under AHS, that they'll send someone out charging $50+/lb, leaving you with a majority of the bill. Unless you have high end appliances, chances are you will definitely spend more on service call fees and premiums than replacing appliances when they near the end of their lifetime, and come close to the cost of a new A/C system in fees, premiums, and freon before they'd replace it instead of repairing (especially considering, at $100 per service call and only $10/lb off freon, I can find HVAC contractors to come out and top off freon for less on my own, in Florida).