Checking the contractor
Who you hire matters as much as the price.
License
Many states and cities require HVAC contractors to be licensed. Look up the license number on your state or local licensing website.
Insurance
Ask for proof of liability insurance and workers' compensation where required.
Refrigerant certification
Federal rules require technicians who handle refrigerants to be EPA Section 608 certified. You can ask if your technician has this certification.
Labor warranty
Ask how long the company guarantees its own work, separate from the parts warranty.