Luggage Storage At Don Muang?

We are flying into Suvarnabhumi from Seoul and then having to transfer to Don Muang for the BKK - Udon flight.

We have 7 hours between flights and with a restless 3 year old son with us, we would like to store our luggage so we can go for a walk to the shopping area across the expressway from DM. We have been in Korea for a couple of years thus my wife and I are very keen on having some Som Tum and sticky rice.

Can anyone tell us if there is a luggage storage facility available at DM?

Thanks

Seykota