Where is this rear cabin heat vent?

[PSC]

I'm the new payment payer of a 74 PA-28-151 Warior. I've seen reference to rear cabin heat vents before and that they may be covered with carpet. I was at the hangar today and got curious to see if mine were. No luck. Where should they be? I attempted to press on the carpet to try to locate covered holes, but didn't feel any.

 

[PSC]

 

[flyguydon]

 

[Orest @ CYFD]

 

[PSC]

 

[Dennis]

 

[flyguydon]

 

[ifly4fun]

 

[47cubpilot]

 

[PSC]