Without a diagram, first determine if it is MOV (varistor) OR NTC (thermistor). Similar packaging but completely different devices.
How can you tell?
NTC (thermistor) is always wired in series with the AC circuit. A low value, heat sensitive resistor that normally takes the brunt of the current while providing an inrush cushion.
Therefore it may fail after certain hours of operation. Specially if it is under-rated or more problems down the circuit.
MOV on the other hand is used as a surge protector and always wired in parallel between the two AC lines. It acts like an open switch and will only crow bar(fail) if it sees a potential higher that its ratings
Also, in majority of cases, MOV failure will blow the main fuse while NTC failure may not.
I agree with spec and it appears to be a NTC . It does appear to follow the numbering system used by ITG, UTI among others. --N15SP015
However, not a bad idea to verify how it is wired on the PCB.
Vtech