Whether your daily commute is long or short, your car's heater and defroster functions are important for both comfort and safety, especially in wet or weather conditions. If you have just noticed that your car's heater or defroster has stopped working, the following information can help you determine the underlying cause and possible options for addressing it.
Blower motor issues
When troubleshooting automotive heater issues, one of the first questions to answer is whether or not the fan is functioning. If the fan is not working on either heat or defrost setting, the solution to your problem could be as simple as replacing a fuse.
Heater and defroster fans in vehicles usually require two separate fuses to supply the power needed for the fan to function properly. If one or both fail, the fan will not operate. In most vehicles, one of the fuses will be located inside the interior fuse block, usually located under the dash. The other fuse will be found in the fuse block located in the engine compartment.
Since each vehicle model and design will differ, drivers should refer to their owner's manual to locate these fuses and determine the size and type of replacement fuse used in their car. If the fuses are undamaged or replacing them does not cause the fan to begin working, the blower motor may need professional repair or replacement.
Heater core issues
If your car's heat and defrost fan is functioning but the air it emits does not feel warm, the heater core may be the problem. Heater cores have some similarities to the car's radiator - both use the circulation of coolant to move heat. The car's radiator works to move the heat out into the atmosphere to keep the engine cool while the heater core uses heat from the heated radiator coolant to warm the interior of the vehicle.
In addition to failing to blow warm air, heater core failure can result in engine overheating issues, intermittent issues with low coolant levels, the development of a fine mist on the interior of the windshield, or finding moisture in the car's floorboard, usually on the passenger side. Because heater core issues can jeopardize the radiator's ability to keep the engine cool, having them repaired is always a priority.
Replacing the heater core in most vehicles is a major repair that requires the removal of the dash and other interior components. To learn more about these and other issues related to heater failure, take time to discuss your situation with a reputable automotive repair shop or auto dealer.