The blower motor is the electrical switch on the interior of a vehicle that allows the driver to control the vehicle’s heating and air conditioning system. It is usually built into the the same control panel that houses all of the AC system controls, and is labeled with numbers and symbols to indicate blower fan speed.
Since the blower motor switch is the direct control for the blower motor speed, when it malfunctions or has any problems it can affect the functionality of the entire AC system and should be serviced. Usually, when the blower motor switch has failed or is beginning to have a problem, the vehicle will display a few symptoms that can alert the driver that a problem has occurred.
1. Switch only works on certain settings
One of the first symptoms commonly associated with a bad or failing blower motor switch is a switch that only works on certain settings. If any of the electrical contacts on the inside of the switch wears out or breaks, then the switch may be disabled in that position and that particular setting for the blower speed will not work.
2. Switch is stuck
Another symptom of a bad or failing blower motor switch is a switch that is stuck, or frequently gets stuck. If the switch or any of its contacts becomes damaged, this may cause the switch to jam, or get stuck when you trying to change the setting. In some cases, the switch may completely seize into one position, which will lock the AC into place.
3. Broken knob
A symptom that is a bit more obvious is a broken knob. It is not uncommon for the knobs on the blower motor switch to break or crack, as they are usually made out of plastic. If the knob breaks, the switch may still work, however, it may be difficult or impossible to change positions on the switch if it is broken. Usually when this happens, only the plastic knob needs to be replaced, not the entire switch.
The blower motor switch is the physical control switch for the AC blower settings, and is therefore critical to the overall functionality of the AC system. For this reason, if you suspect that your blower motor switch has a problem or fault, have the vehicle’s AC system diagnosed by a professional technician, such as one from YourMechanic. They will be able to replace the blower motor switch or make any other repairs that are appropriate.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Blower Motor Switch and was authored by Ed Ruelas.