Your formula is correct.
I don't know why you have 4.87 V in the formula. It is better be the Voltage at the V ref pin.
If that is the voltage being taken at the cathode of the LM335, and ( hopefully ) connected your circuit properly, Anode of the LM335 to gnd, and the rest of the circuit, I got the feeling the LM336 may have an open - or damage. ( hope not )
One thing is sure. the analog pin see a open voltage - Full Vcc, if you Vcc is 4.87 V.
My opinion