ARS-American Residential Services - charges an exorbitant 'parts' charge rather than time and materials. They replaced a capacitor and relay and charged my 87 yo mother $681 and then tried to sell her a new unit to boot.

Stay away from these guys!

Use a company that charges time and materials.

With ARS, you'll get a novice repair man with incentives to put in parts you don't need. The more parts, the higher the cost (like $300 for a $20 capacitor!). Then they'll try to sell you a new system that you don't need. Horrible company; they are all over the place too!