the temperture inside my PJ is always higher than outside why

WHAT?

Do you have the heat on? I don't get the question.

That's why I said "WHAT?"

the therometer reading is 25 degrees while outside the car it will be reading 21 degrees. my heater is off meanwhile

I'm really trying here, but I am still baffled about what your problem is. Does the heater not work, are you using northern and southern thermometers at the same time? If you turn on both the heater and a/c at the same time a polar vortex forms by the radiator,, and you will have to shovel out in the morning. Hope this helps.