UTH isnt getting hot enough(plastic tub enclosure)

[Mc.mischievous7]

Check the temperature of the plastic bottom just over the UTH. Are you getting 85f ambient or hot spot?

If the temperature of the plastic is low just over the UTH try plugging the UTH into a receptacle without the thermostat to see if it's a faulty thermostat. Without the thermostat the UTH should get the plastic pretty hot. (Only do this temporarily to see if it's working)

Sorry for asking this dumb question but what exactly is ambient temp? But I'm using a temp gun on his hot side.