Checking the defrost sensor—also known as the defrost thermostat or outdoor coil temperature sensor—involves inspecting its physical condition and testing its electrical resistance using a digital multimeter. First, turn off the electrical power to the outdoor heat pump unit at the main breaker panel for safety. Remove the exterior service access panel to locate the sensor, which is typically clipped directly onto the copper tubing of the outdoor coil. Inspect the wiring harness and sensor bulb for corrosion, loose connections, or physical damage. Next, disconnect the sensor wires and set your digital multimeter to measure ohms of electrical resistance. Measure the resistance across the sensor terminals and compare your reading against the manufacturer's temperature-resistance chart for your specific heat pump model. You can verify that the sensor is healthy when its resistance changes predictably in response to temperature variations or matches expected specifications.
1 votes
Marked as accepted