Arcoaire

I have to replace my 19 year old central air conditioner. I’ve been getting quotes and most businesses recommend replacing the furnace also. The quotes range from $5300 for a top of the line Lennox unit up to 7000 dollars for a Carrier (a quote from sears) I am getting another quote from somebody tomorrow and he originally estimated about $3000 and he uses arcoaire. I would like to get some feedback about this brand. I haven’t read any great recommendations for it.But for the price difference , it is had to pass up.
BTW. I live in a 2 bedroom, 2nd floor condo.

Thanks

There may be more, specifically Arcoaire, experience on this board:
http://www.hvac-talk.com/vbb/showthread.php?t=106468