Do you have a temperature probe directly on the glass where the UTH is? UTH's do not change the temperature of the air in the cage, so unless you have a probe directly on it you cannot tell how hot it is.

Why is it on the side? Heat rises, it does not move horizontally (they are called Under Tank Heaters for a reason lol)

UTH's can and will get extremely hot, 150+ degrees. this is hot enough to kill your snake. a thermostat is an absolute necessity.

Here are 2 good ones, the ones sold in pet stores are crap.



http://spyderrobotics.com/


It sounds like you heat lamp is creating the hot side fine on its own. For now I would just unplug it