An HVAC electronic control module is one of many computers inside your vehicle. It controls and regulates the heating, ventilation, and air conditioning (HVAC) system, much in the way a thermostat controls the temperature in your home. But this electronic control module is a bit more complex. Not only does it set the temperature for as many as four zones in your vehicle, it also controls the amount of air flow and the direction the air flows through the vents. The HVAC electronic control module even controls other components, such as the air conditioning compressor and thermal expansion valve.
The control module receives input from a host of sources, including the user control panel, temperature sensors inside and outside your vehicle, and more. Data from these sources help the control module to automatically control the HVAC system.
The HVAC electronic control module directs all of the operations related to the climate control inside your vehicle. Because it touches many different components, from the blend door that alters the temperature inside the cabin to the thermal expansion valve that regulates pressure in the AC system, any signs of a bad control module might instead point to some other failed component. For this reason, it is essential that a qualified technician perform an accurate diagnosis before replacing the control module.
Although they could point to other problems as a source, signs that the HVAC electronic control module is failing include: