STEP 1 Turn off power. STEP 2 Remove Thermistor wires from where they are connected. STEP 3 Set the Multimeter to the Ohms and select a scale to measure up to approximately 300K ohms. STEP 4 Connect one of the Multimeter leads to the Thermistor wire and the other lead to the other Thermistor wire. Do not touch the leads or you may change the resistance reading. (alligator clips may be helpful to do this) STEP 5 Compare the resistance reading to the below chart. The resistance will change depending on the temperature. STEP 6 If the resistance reading is more than 10K ohms outside the range in the chart below it should be replaced.