My air conditioning is blowing air but not cold. I had to open the top of the unit to remove a piece of plastic being hit by the fan. It was blowing cold air before I opened the top. It is now working running fine but not cold like it should be. I have since opened and checked all wire connections, everything is still connected,and checked to see if anything else was out of place. It doesn't seem that anything is different from when I opened the top and then replaced it. Any other ideas?

Dirty air filter? Dirty outside coil? Is the outside unit running?

The outside unit is working, the air filter is clean, the coils are moderately dirty. I opened the unit at 3p.m. to remove a piece of plastic and at 4p.m. it was working fine but not blowing cold. I wish I hadn't opened it to begin with.

What was this piece of plastic that the fan was hitting? Is it possible that the coil was damaged by this plastic ? Do you see any oil on the coils?(indicate a leak) Is the compressor running ?

Check to make sure all wires are connected, it is possible that removing the cover caused a wire to come loose.