You’ll want to look for a manufacture date. This is frequently situated on a label on the outside of your unit.
If your equipment is under five years old, it might still be warrantied. However, warranty terms and conditions vary between manufacturer and installing company.
At Aramendia Plumbing, Heating and Air, we can verify your warranty state with a system inspection. We also have HVAC service memberships in San Antonio for residential heating and air conditioning units, regardless of equipment age or manufacturer warranty standing.