Went on a no cool yesterday on a new install. Homeowner said system worked for about a week and then stopped cooling. He said that there was a noticeable difference in the amount of air coming from the supply's, said that it is a lot less. Took amp and volt draw on blower motor, had 5.4 amps and 120V. System is 3 tons at 1200cfm. Went in attic and looked for kinked ducts, etc, none found.
Made sure speed taps were on correct spades. Took cover off of A coil and looked for obstructions, none found. Touched side of motor and hello howdy was it hot. I know that is not right so I am going to replace the motor on Monday. How can you tell if the motor is putting out the correct CFM at the air handler?
One oddball thing I did find is that the return static pressure is
1.0. The return duct is sized properly but when I went in the attic I could hear the air rushing through it about two feet after the filter grill. The noise is in one spot only, not the entire duct. Before the install the duct was doing this and it was routed so that it was pinched off in two places. Had the installers re-route it and it's still making this noise. Also, the static pressure on it was 1.0 before they re-routed it. I thought it was being caused by the duct being pinched off but I guess not. If I run the system with the blower door off the static drops to 2.5, however, the airflow in the house stays the same.