-17966.20 does seem a little bit cold for most offices. Did you change your variable array so it has the
ds18Temp named variable in it instead of the other new variable? If not update step will update that other new variable and not the one that you’re calculating F from, though adding the “true” to the getValue should force it to update anyway. Is the Celsius temperature from the DS18 reasonable?
Using true*1.8+32 will give you 33.8 no matter what happens. In the multiplication “true” is converted to “1” so your equation is just (1*1.8)+32 = 33.8.