Your air-conditioning vents have those little adjustable levers, so it must be alright to close them in unused spaces, right? Not necessarily. The main issue is that air pressure rises in the duct system with every closed vent, which could cause the following problems:
· More duct leakage.
· Lower air flow (with PSC blowers).
· Increased energy use (with ECM blowers).
· Low air flow leading to uncomfortable conditions.
· A frozen air-conditioner coil.
· A dead compressor.
· A cracked heat exchanger. Carbon monoxide may leak into your home.
· Increased infiltration/exfiltration due to unbalanced leakage. Condensation and mold growth become possible.
Why risk any of these problems for a few closed vents?
Read the full article here: Is it Okay to Close Air-Conditioner Vents?