Delete cell contents if another cell is blank

Hi, I daily download data into a spreadsheet and I need to be able to delete the contents of one particular cell if another particular cell has no data in it.
The cells are in the same row as each other, but the actual row number can change depending on how many rows of data the download contains.
The columns that these cells appear in are always constant.

I need a macro function that will look at the whole worksheet and repeat this process wherever it finds this condition.

For example, if cell L4 is blank, then delete the contents of cell U4. Then repeat this for the rest of the worksheet.
Cols L and U will always be where the cells reside but the rows could be anywhere. The worksheet range is from A1 to AN400

The sheet is overwritten daily by the new download so I can't use a formula stored in a cell.

I already have a macro that performs other formatting on the sheet, so I need to add code to the beginning of the existing macro.

Sorry for the long message but I tried to be as descriptive as possible.
Thanks in advance for any help
Mike