I check the LM335 datasheet. You Resistor connected to the two LM335 is WAY LOW Man... A 220 ohms, I bet the inside must be very warm. That might explain the high reading. Can you change it to a 2.2 K ohms ? That will put the reverse current below 1 mA. The LM335 is a variable Zener diode. A zener doide will begin to conduct in the wrong way at a certain voltage. In the case of the LM335, it ia about 3 V. So you limit below 1 mA, you do the Resistor Limiting Formula :
( V in - V diode ) / The limit current = The Limiting Resistor
Try it, and see what happen.