Is the compressor on all the time other then when the unit is in a defrost cycle?
You can usually hear it but also should be able to feel it vibrating.

If yes you have to pull the rear cover in the freezer and inspect the evaporator coils.
If they only have frost in one area (usually where the freon enters the coils) (see below) then you probably have a low freon condition.

This will be an expensive repair as you need a pro.
There is no use just adding freon, the leak should be found and repaired.

http://www.applianceaid.com/ref...ator-not-cold-enough.php
See the example pictures about half way down the page.

[COLOR="Blue"]Thanks for the reply, Denman, yes the compressor stays on all the time and there is a block of ice where the freon enters the coils,[/COLOR]
To double check for low freon unplug the unit and defrost the evaporator coils.
Do not use a knife etc. to chip off the ice.
You can use a hair dryer to speed it up.
Then plug the unit in to see if frost just develops in that area.
if yes then it is low freon.

[COLOR="Blue"]wouldn't you be able to visually see a freon leak from residual oil somewhere ?[/COLOR]
No. It depends where the leak is.

[COLOR="Blue"]If there were a leak ? If it is a leak then I should probably return the jazz board I bought and get someone out to detect the leak and fix it.[/COLOR]
I cannot say as this is a personal choice.
You could get a couple quotes on what it will cost.
It may require a new compressor so get quotes with and without compressor replacement.
A lot depends on what kind of shape the unit is in and what a replacement unit that you would be happy with is going to cost you.
I would return the jazz board.

I would check the warranty on this unit.
Often the sealed system has a longer warranty.
You have to also check the terms because it sometimes just covers the parts.