Freezer motor cuts in and out. Runs for about thirty seconds at a time. Now have red low temp light on and everything is defrosting. Sides of freezer used to be very warm and are now cold.

Good day,
Some kind of compressor problem. If it will run a true 30 seconds then it is either the start relay mounted on the side of the compressor hanging up and not releasing after the compressor starts or the main windings in the compressor are starting to short, causing the compressor to draw too much current followed by the protective overload shutting the compressor down.
The relay is pressed onto the compressor pins and can be removed.

A parts house should be able to test it for you. If bad, replace. If it tests good then the problem is internal to the compressor and would need the attention of a qualified tech.

P.S. If the unit is under 5 years of age, leave it alone and call for factory service. It may or may not be covered but if so it would be necessary to preserve the balance of the 5 year warranty.