When Pulte built my home they selected Sierra, who installed a York A/C unit that failed due to tube joint fracture after just 3.5 yrs. The unit is under a 10 year warranty (parts, not labor) from York, which the nighttime tech and his call-in manager (worryingly) did not acknowledge, but that the day manager corrected the next morning (without my prompting or arguing about it--he called me to correct this). Since this York A/C condenser manufacturing series had some known issues discussed in on-line forums, Sierra quoted a fair, low, price for labor and a completely new condenser & refrigerant, to eliminate all doubts about keeping the failed one as a repair job. As I would have been on the hook either way for the labor, the difference in cost I paid to obtain an all new piece of equipment I think is very fair and reasonable. They did a detailed quality job of cleaning, vacuum drying and testing the refrigerant loop and installing a new in-line filter. They showed up on the days promised and did quality work without rushing through it, answering all my tech questions (I'm an engineer). We confirmed the system is supplying the expected amount of cooling for the measured amount of power it is consuming. I don't have enough data and experience to say that York is a brand I'd recommend--time will tell--but as for Sierra's contracting, they did a good job in both the actual work and in communicating the details of the issues. The three techs I worked with arrived clean, behaved professionally, communicated intelligently, were well trained, and drive a clean well organized truck.