How to check the temp. sending sensor???

Can anybody tell me how to check the temp. sending sensor??? Not sure but the temp. will move from 215 down to like 195-200 and back up to 215 realy fast not sure whats going on. New radiator, hoses, fan clutch, tstat, water pump. ????????????? thanks in advance.

Joe

Is this a factory guage ? What you are most likley seeing is the theromstat reaching opperating temp and then opening.Thus the hot-cool-hot normal running temp.
Wayne

you can use an ohm meter (radio shack has them). you jeep should read from 970 ohms (194 deg) to 720 ohms (212 deg farenheit). also you might still have air in the system making the readings go all over the place. you let the motor run with the radiator cap of till it reaches operating temp. the thermostat will open letting the air out fill the radiator back up with some water. make shure you have the temp set to hot on your heater in the car.
hope this helps.