HVAC Diagnosis Made Easy: Blend Door, Blower, and A/C Testing With a Bidirectional Scanner

About this video

LIVE DATA WE LOOK AT
Blend door actuator commanded position versus actual position
Mode door and recirculation door position feedback
Evaporator temperature sensor
In car temperature sensor and ambient air temperature sensor
Sunload sensor
A/C refrigerant pressure sensor reading in PSI or voltage
Blower motor commanded speed and blower control voltage
A/C compressor clutch or compressor control request status
Engine coolant temperature, which the module uses before it allows full heat

ACTIVE TESTS AND BIDIRECTIONAL CONTROLS DEMONSTRATED
Commanding the blend door actuator from full cold to full hot and listening for movement
Cycling the mode doors between panel, floor, and defrost
Commanding the recirculation door open and closed
Running the blower motor through low, medium, and high speeds
Commanding the A/C compressor clutch or compressor relay on and off
Commanding the cooling fans on to verify condenser airflow
Actuator calibration or relearn after a repair, which many vehicles require