[SIZE=4]checked for continuity on thermistor and get nothing. putthermistor in boiling waterand still no continuity. what is the function of thermistor andwhat sould resistance be for heating element[/SIZE]
Here is your tech sheet
http://www.servicematters.com/docs/wiring/Tech%20Sheet%20-%208537797.pdf
The thermistor senses the water temperature, if blown the cycles will be longer as the unit is waiting for the water to come up to the correct temperature.
Note: That it is a negative device (resistance drops as temperature rises)
If infinite ohms (open) it is blown. Just be sure that you have the meter on a high enough scale.