- Blend Door Actuator: The blend door actuator is responsible for controlling airflow by adjusting the position of the blend doors in the heating, ventilation, and air conditioning (HVAC) system. If the actuator fails, it may cause the system to stick on defrost.
- Climate Control Module: The climate control module is a computer that controls the operation of the HVAC system. If the module fails, it may cause the system to stick on defrost.
- Wiring Issue: A wiring issue in the HVAC system, such as a broken or disconnected wire, may also cause the system to stick on defrost.
Solution:
- To diagnose the issue, a mechanic will first check the blend door actuator and the climate control module. If either component is found to be faulty, it will need to be replaced.
- If the actuator and the module are both working properly, the mechanic will check the wiring for any issues. If a wiring issue is found, it will need to be repaired.
- Once the problem is diagnosed and repaired, the HVAC system should function properly again, allowing you to adjust the airflow as desired.
