Best place to start looking is on the outside parts of the unit for a manufacture date. Typically if the equipment is less than 5 years old it most likely will still be under warranty. Each manufacturer is different so warranty terms may vary. The HendrixAir team can verify the warranty status of your heating and cooling system via System Inspection. We also offer a VIP Maintenance Agreements for residential heating and air conditioning systems, regardless of how old your equipment is or manufacturer warranty status.