Standing water in the bottom coolers of my prep table.

The drain tube that drains out the water is plugged. It runs from inside the cabinet to under the refrigeration unit outside the cabinet. Try to clean it out with a can of compressed air used to clean keyboards and see of that works.

drill a hole and insert a piece of tube from home depot 3.00

This will help You. I had to replace compressor. It died due to the 100% clogged coils. REPLACING COMPRESSOR TRUE AIR BEER COOLER R134A

I made video how to replace compressor on true air beer cooler, should be the same for most of prep tables and etc. Hope That helps someone. REPLACING COMPRESSOR TRUE AIR BEER COOLER R134A

Keep the prep top table pans covered when not in use. Never leave empty holes where pans should be. If the pans are empty put a couple of inches of water in them to keep some heat load there. Check the door gaskets and door seal on the base doors. Make sure the thermostat is set on number 5. If all of this checks out probably need a new thermostat, but if it's erratic I suspect you will find it's one of the former problems.

you need to blow out the drain with some compressed air and clear the obstruction.

Most all manufacturers try to build units to hold between 34 to 38 degrees as this is the most commonly accepted range for coolers by all Health Departments.

During the cooling/freezing cycle condensation forms, this drips into a pan and then is evaporated by a heating element.
One of two things could be wrong.....
Your drip pan is clogged
or
your evaporator unit is bad

Hope this helps

there are defrost heaters in this unit also the fan that is on the top plate could be resting in water. put the init into a defrost and after all the ice has melted clear the drain line thats by the fan on top. while your are looking check the wireing to the axiel fan there.