When a blower resistor fails, the highest fan speed usually is the only one that still works because it essentially bypasses the resistor and receives the maximum amount of voltage. When the resistor is working, it reduces the amount of voltage going to the lower fan speeds, so the fan runs slower.Jan 17, 2016
Why does my blower fan only work on high?
Most car manufacturers use a series of resistors to make the heater blower motor run at different speeds. And when one or more of these resistors burn out, you're usually left with only one heater blower motor speed—high. ... Remove the screws, and swap out the resistor module.
How do I know if my blower motor resistor is bad?
- Only One Speed From Blower Motor. One of the most common symptoms of trouble with the blower motor resistor is when the fan gets stuck in one setting. ...
- Various Airflow Settings Not Working. ...
- No Air Coming From Vents.
Is it better to run AC on high or low?
Set the fan speed on high, except on very humid days. When humidity is high, set the fan speed on low for more comfort. The low speed on humid days will cool your home more effectively and remove more moisture from the air because of slower air movement through the cooling equipment.
Why does my AC only work on hi?
If your air conditioner works on high, it is a very specific issue. It can mean that there is a problem with the blower motor, the control board, or the thermostat. However, we still do a full diagnostic check-up to ensure that all of the switches, wiring, and fuses could not be causing the same issue.