Two years ago they came when I needed them because my air was dead, they fixed a dead "cap" but then told me there was a leak and I'd need a new system for $6K. I had a second opinion done by another company (Integrity Air, certified by Rosie On The House) and he said the Freon was probably low from years of A/C techs hooking up their equipment for my annual inspections and a little leaked out each time. He said he couldn't find any evidence of a leak. This was after I had paid over $300 for Precision to do a "leak test" which consisted of going up in the attic for about 4 minutes and making some beeping sounds....at that rate those tests are apparently $4500 per hour!. I'll never use Precision again.
UPDATE 2 years later... The system that these con-artists said needed replacing is still working great.