How does a fan resistor work?

How does a fan resistor work?

The fan speed can be changed either by switching the blower resistor resistance mechanically using a rotating lever, or electronically by the air conditioning system. The change in resistance then limits the current through the motor, which dictates the speed at which the blower fan operates.

What is the resistance of a fan resistor?

Again, ohms law suggests that at full speed this fan has a resistance of 5.2Ω so adding an 11Ω resistor in series should drop the overall current to 0.74A (8.9W rather than 28W) with 6W through / 8.1V across the resistor and 2.9W through / 3.852V across the fan.

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.

How is a blower resistor used in an air conditioner?

Blower resistors are resistors which are used to control the fan speed of automotive blowers. The fan speed can be changed either by switching the blower resistor resistance mechanically, using a rotating lever, or electronically by the air conditioning system.

How can I change the speed of a 12V fan?

Here is a simple mod to allow the speed of any 12V fan to be varied. All we need to do is insert a rheostat or variable resistor in the 12V wire to the fan. The rheostat should be rated at least 3 Watt, (for fans up to 10Watt), and have a resistance of 20 – 50 Ohms.

What are the symptoms of a bad blower motor resistor?

Blower motor stuck on one speed. A common symptom of a faulty blower motor resistor is a blower motor that is stuck on one setting. Blower motor does not work on certain settings. No air from the vehicle’s vents.

What is the fan speed?

Most equipment comes with the fan speed set in cooling mode at 400 CFM/ton. The greater the airflow over the coil, the less humidity you remove, so if you live in a dry climate, you can set the fan speed up to as much as 450/ton to get more sensible cooling and less latent.

Where is the blower motor resistor located?

The blower motor resistor is located under the dash on the right hand (passenger) side. It’s near the firewall, just below the windshield.

How does a blower motor resistor work?

A blower motor’s speed is adjusted with a blower motor resister. A blower resistor uses resistance to control the speed of the blower motor. In high speed, the resistor is bypassed and power is fed to the motor directly from the switch.