# How does a resistor control fan speed?

## How does a resistor control fan speed?

This means that the current running through the blower motor, and thus is speed is controlled by the resistor value. The lower the resistance of the selected resistor in a pack, the higher the current that flows through the blower fan, and the faster the fan will turn.

How can I speed up my 12V fan?

The correct answer is use a bigger fan of same 12V rating which draws more current. However, if fan can not be changed but a slightly higher cooling is desired then you can try feeding 13 V power supply to a 12 V fan. Mostly it would run at a slightly higher speed.

How does resistance affect the speed of a blower fan?

The lower the resistance of the selected resistor in a pack, the higher the current that flows through the blower fan, and the faster the fan will turn.

### What happens when a cooling fan resistor fails?

The cooling fan resistor is meant to send power to the fans in steps, so that the fans may operate at different speeds. If any of the individual steps or switches fail, it will disable the cooling fans from operating on that speed setting. You may notice that the cooling fans only operate at one speed, when they used to operate on two or more. 3.

How does the speed control on a ceiling fan work?

For instance, when you switch from medium to high on a solid-state fan, the speed control mechanism increases the power of the motor. Solid-state controls are generally equipped in fans with controls that have predetermined settings, such as low, medium and high.

How to control the speed of a PWM fan?

For PWM, by means of applying voltage on and off, the amplitude should be equal to the nominal voltage of the fan, the frequency should be held constant (<1kHz recommended) and the duty cycle allowed to vary between 0 and 100%. The voltage must be current limited so that there is no more than 5mA to the program lead.

#### Are there low, medium, and high speed fan relays?

Coming out of the BCM, there are two lines. One for low speed, one for medium speed, and both for high. The 5 fan relays change that into 3 wires going to the fan module: low, medium and high. (There’s another wire somewhere for the ground return.) In the fan, the low and medium run though resistors and a thermal fuse.

How does a blower motor resistor control the fan speed?

The blower motor resistor controls the fan speed of the blower motor and the resulting change in air pressure produced by the movement of the blower fan. It accomplishes this by regulating the electric current that powers the motor.

Can a high speed fan have low resistance to ground?

At least one fan terminal will have a low resistance to ground (or the fan wouldn’t run at all). But if one of the other terminals are missing resistance to ground within a few hundred ohms or so, that speed is bad. If you just measure between the terminals, you should show resistance between each one – but if they’re bad, you won’t have any.

## What are the relays for the radiator fan?

The 5 fan relays change that into 3 wires going to the fan module: low, medium and high. (There’s another wire somewhere for the ground return.) In the fan, the low and medium run though resistors and a thermal fuse. High is direct and bypasses the thermal fuse.