Number 1 if that is true you have a problem and need to get a new uth. If it never goes above 85.f then you're not providing the Correct hotside temps and you're going to have a snake that 1 will nor eat or 2 cannot digest what it does eat. Or it will become Ill from incorrect temperatures.

Number 2 If that happens to be not true without a dimmer (rheostat) or a thermostat you still have a problem.

So personally I would make sure that you have a uth that is compatible with the animals basic needs. You need a uth that goes above 85.f. If it truly doesn't then I would get a different one.
If it does I highly suggest getting a plug in dimmer for now. You'll have to fiddle with it a bit but I would also order a Hydrofarm. Theyre an affordable, Yet reliable thermostat that is easy to use, and saves you a hell of alot of trouble in the end. Good luck

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