Conditional Text Deletion From Cells

I'm getting a type mismatch (Runtime Error 13) with this code. What I want it to do is delete the contents of the cell if it contains 'N/A'.

Sub RemoveNAs()
Dim word
word = "N/A"
For Across = 1 To 5
For Down = 2 To 150
Cells(Down, Across).Select
If Cells(Down, Across) = word Then
Cells(Down, Across) = ""
End If
Next Down
Next Across
End Sub