How to deal with temp sensor input

Hey Guys
I'm new to the Arduino and I'm trying to read an input from a circuit I've made. It uses a PT1000 sensor and outputs 10mV pr. 1 degree celcius (0mV = 0 degree, 1000mV = 100 degrees)
At the moment I'm monitoring the value via the serial monitoring, but I always gets the same results no matter what I do to the sensor, so I began to consider the resolution and how to Arduino is actually reading and I was hoping some of you could tell me how it works.
It shows 37x to begin with and then drops to around 26x/27x and the value just stays there.
I've added my code so you can se what I'm currently doing. I didn't add the loop since the only thing I'm doing there is just calling my ReadTemp()

void setup()
  //pinMode(fanPin, OUTPUT);
  Serial.begin(9600); //set the baud rate
  Serial.flush(); //flush the buffer to empty

int ReadTemp(void)
  int tempValue = analogRead(tempPin);


Thanks in advance

We really need the see the whole sketch.

The part you posted is okay.
The Serial.flush is not needed and I would use the 'println' for the temperature and there should be some kind of delay in loop().

But what is tempPin ? Perhaps you are reading the wrong pin.
Can you measure the voltage of the analog pin with a multimeter ?
What does the circuit look like ? Show us the schematics, perhaps even upload a photo.