PLEASE HELP ENGINEERS

brianrichard1120 

Does this work better?

Sub CleanAC()
    Dim LastRowPYA As Long
    Dim CharacterArray As Variant
    Dim Character As Variant
    CharacterArray = Array(Chr(58), Chr(92), Chr(47), "~?", "~*", Chr(91), Chr(93))
    Application.ScreenUpdating = False
    With Worksheets("Invoices")
        LastRowPYA = .Cells(.Rows.Count, "A").End(xlUp).Row
        With .Range("AB1:AB" & LastRowPYA)
           .Replace What:=Null, Replacement:="BLANK", LookAt:=xlPart
           For Each Character In CharacterArray
               .Replace What:=Character, Replacement:=Chr(32), LookAt:=xlPart
           Next Character
        End With
    End With
    Application.ScreenUpdating = True
End Sub

And perhaps you should change

LastRowPYA = .Cells(.Rows.Count, "A").End(xlUp).Row

to

LastRowPYA = .Cells(.Rows.Count, "AB").End(xlUp).Row

but I cannot judge that.