See previous thread:
http://www.fairfaxunderground.com/forum/read/2/370169/604705.html#msg-604705
I do not wish to slander anyone here so just let me say that my previous experience with ARS and a few others has been bad in my opinion.
Ars was at one time known as General heating, Keenan and a few others that were bought out (a couple times i think) by a huge coperation. Those reliable, honest privately held companies provided a good value for their clients in my personal opinion. You can form your own opinions about the current owners. I now use a contractor from manassas that I love. Advanced heating and air 703-791-6500. Im not sure if they service all of NOVA but they do work in centreville and clifton. The owners name is George.
The down side to using a small contractor is that they dont do 24 hour service and they get backlogged with work in hot weather but at least they are more likely to be straight with you.
I dont like being without A/C so I keep a couple small window A/C units on hand in case of emergency.