PTC Thermistor?

Hello,

First of all, I am new to anything involving Arduino, so I apologize if i sound like a noob. I have a bit of an issue. I've recently bought an Electronic Brick Temperature Sensor that uses a thermistor to measure temperature. After a little reading, I found out about NTC and PTC thermistors. I made a little program just to see the raw reading from the sensor. The value I get decreases if I heat up the sensor. After that, I tested a few programs found on the web to see the ambient temperature. The temeprature seems fine, but when I heat the sensor, the temperature also decreases, just like the raw value. I think it is a PTC thermistor. Most of the programs tested by me use the Steinhart equation to calculate temperature, but all of them are for NTC thermistors. Until now, I haven't found a single example for PTC temperature calculation. What should I do? I tried reversing the wires, but the voltage regulator on the brick doesn't like that, as it gets hot, and temperature is not accurate anymore, but it DOES rise if I heat up the sensor.

Please help...

These things don't attract much interest, but here is some background.

http://openenergymonitor.org/emon/buildingblocks/rtd-temperature-sensing