ACS did a FANTASTIC job for us. We found that the technicians were very knowledgeable and honest. They did a whole-house assessment including air flow and proper size for the HVAC unit we wanted. 
 
ACS did not push us into any service or product. They did offer a new furnace when I asked about our 15 year old furnace. They also installed an Amana refrigeration unit (4 tons) and the new gas furnace. 
 
I give them 10 stars for quality, affordability and knowledge.