A animal was scratching in the upper heating part. I called an exterminator. I was afraid to let it out into the basement. Then I didn't hear it and then clog and water on the floor. I called the HVAC in and he found a bird in the top part of the heating unit. Then another clog and he found a clog in the pvc pipe not. O-K now I do not understand how a bird got into the system. This is a tall 2 family house and who do I call in and where should he check for an opening. I did have a new roof installed after Sandy just thought I should state this also. Thanks for your help. I wish I got the bird out safely but it was so loud I thought it was something larger and was afraid. Could I be missing a vent cap or where can a repairman look and what kind of special specially do I call in to figure this out.