You’ll want to find a production date. This is typically located on a label on the surface of your unit.
If your system is newer than five years old, it may still be under warranty. Having said that, warranty terms and conditions vary between manufacturer and installing company.
At Gordon's Service Experts, we can confirm your warranty state via a system inspection. We also offer HVAC service memberships in Oklahoma City for residential heating and air conditioning systems, regardless of system age or manufacturer warranty standing.