Question 81Refrigeration & AC - QMED

The correct answer is C) When checked with control power on and the thermistor probe connected into the circuit, the thermistor probe voltage drop should be 3.805 volts. This is correct because at a supply water temperature of 45°F, the thermistor probe's resistance will result in a voltage drop of 3.805 volts when the probe is connected into the circuit with control power on. The thermistor probe's resistance changes with temperature, and the chart provided illustrates the expected voltage drop at different temperatures. The other options are incorrect because option A assumes the probe is isolated, option B gives an incorrect voltage drop, and option D assumes the power is off, which would not provide the necessary voltage to measure the thermistor probe's resistance.