My ac unit is not cooling, the large copper line is cold but not super cold, my husband changed the filter and we set the ac to 78 and it has been at 81 for about an hour. What other things should we check for before we call an AC repair person.

How long has the unit run? One hour or?

We turned if off last night and turned it back on an hour ago.

FYI: We were out of town for several days got back, turned on the air and during the night we woke up because it was very warm, so we decided to turn it off and go sleep downstairs and use our other unit. In the morning my husband changed the filter and left to work. I work from home so decided to turn it on to see what happens before I call.

Is the other copper line warm or hot?

Warm

Let the unit run for 6 hours or so and then take the temperature at the return and supply air so we can get a differential.

Will do!