Error 1004 - Method Range of Object Worksheet Failed

I'm getting error 1004 - Method Range of Object Worksheet Failed for the lines highlighted red below, and can't understand why or how to fix it. Could someone please point out what I am doing wrong?

Dim c As Range

With Sheet1
LR = Range("B" & Rows.Count).End(xlUp).Row

    For Each c In Range("A3:U" & LR)
        If IsEmpty(c) Then
            Range(c).Interior.Color = RGB(245, 0, 0)
        Else
            Range(c).Interior.Color = xlNone
        End If
    Next
End With

End Sub