Knocking/Vibrating noise behind AC vents

[CoolSwitch]

Need help identifying what causes the vibrating/knocking sound behind AC vents.

After a mins na AC was turned on, you'll hear the noise, and once pinatay ang AC mawawala din yung noise

TIA

[jick.cejoco]

Need help identifying what causes the vibrating/knocking sound behind AC vents.

After a mins na AC was turned on, you'll hear the noise, and once pinatay ang AC mawawala din yung noise

TIA

might be FOD (foreign object debris) or a thermistor that came loose from the mounting and oscillating. vehicle make, model, year, mileage, last thing done to it prior to the symptoms?

[CoolSwitch]

Toyota Corolla 94

last thing done:
-just had the AC cleaned, and hinang daw sa evaporator (may tama daw kaya may tagas)

[emjay72701]

Ipasilip or ipadinig mo sa gumawa dati baka under warranty pa at wala naman charge.

[EE100shiro]

kung may tagas evaporator mo wala ng freon kinabukasan