I live in a condo in Phoenix. Recently the closet ac has starting acting up. I checked and replaced the air filter. It was dirty and I must admit it had been a while since I had replaced it. The air flow is still weak though. However, when I remove the cover to the ac unit, the airflow greatly improves and cold air begins pumping into the entire condo. I think the problem has something to do with lack of air flow through the vent but I have no idea what might be causing this.