I have lived in this home for 4 years and I have a Home Buyer's warranty on the house and I felt that my a/c unit needed maintenance/tune-up. But since there is a home buyers warranty on the unit, George Brazil would not even come and do the tune-up! This tells me that they are only interested in finding something wrong with the unit so that they can sell me stuff.
UPDATED 6/9/2015: My home warranty does NOT cover ongoing maintenance and it is NOT voided if I have it performed.