You’ll want to look for the date it was made. This is usually situated on a label on the exterior of your unit.
If your system is under five years old, it may still be warrantied. However, warranty terms and conditions vary between manufacturer and installing company.
At TML Service Experts, we can confirm your warranty status through a system inspection. We also have HVAC service memberships in Boise for residential heating and AC units, regardless of unit age or manufacturer warranty status.