Frost is not a big deal as long as it melts as soon as the compressor cycles off. It means we are pushing the air conditioner as cold as it can go. It will be more obvious on hot days, when the door is opened a lot or when you put a lot of hot product into the cooler.
For ice that doesn't go away you need to defrost the AC (first unplug the CoolBot) by unplugging it, turning it off or setting it to the fan mode as long as your fan isn't catching in the ice. You can also use a hair dryer to melt the ice faster. It's important to figure out why you had a freeze-up in the first place. The most common cause is dirt or dust, so be sure to clean your air conditioner thoroughly!
If the ice has formed from the bottom up you could have a clog in your AC drainage. Be sure that the condensation can drip freely out the back. If the condensation cannot drain freely: (1) if the A/C is a model with a plug, open the plug, (2) clean out any jams in the drain, and (3) be sure the AC is tilting slightly down towards the back (exterior of the cooler). Be careful opening the plug for the first time - often a lot of water can spurt out!