The high speed on the A/C blower works but the lower speeds do not. How do I get the lower speeds to work again?

you need a blower motor resistor to get all the speeds again.

Hello sanjuis24
It sounds like you've got a bad blower motor resistor. The resistor is located under the right side of
the dash at the blower motor. A new resistor is not very expensive and it's a fairly easy DIY.
Hope this is helpful

check fuses, then wiggle speed control while moving, may need new dash control for lower speed, usually high speed works through relay may be the reason high speed works

Hi!!
The Blower Motor Resistor also called Manual Temp. Control resistor), is fried, replace. The price with floor console $25 and without floor console $65. here is a pic.


the resistor is located on the blower motor housing, fastened by two screws. It is the part where the electrical plug connects, the plug on the pic. goes to the blower motor.
A HELPFUL - 4 THUMBS rating for this solution would be greatly appreciated. Thank you for using FixYa.

ITS THE SPEED RESISTENS THAT HAS BURNED,THE FAN HAS ONLY ONE SPEED , AND THE RESISTENS LOWER THE SPEED IN STEPS , GET A NEW ONE AND IT SHOULD WORK

The high blower works off a relay in the high speed only so the fan switch is at fault on your vehicle
Replace the fan blower control speed switch which is the one you adjust the lower fan speeds

The switch, high blower speed relay or the wire harness at the blower motor has gone bad. The highest setting 5 has no resistor, so the blower runs on high but the high current flow ends up burning up the switch's contact on that setting or the relay and may be the resistor wire harness at the blower motor has gone bad. Common would be the switch it self, if the switch is good. Then it's going to be the blower relay or wire leads at the speed resistor by the blower motor under the glove box by the passenger leg compartment. Keep me posted, be glad to help you get your Silverado running 100% again soon.

The resistors provide resistance in the circuit, dropping voltage to the blower motor to slow the motor speed down. On high, the blower receives full voltage through the blower relay.

If you had High but no other speeds, then the resistor pack is usually the culprit. If you have all other speeds but high, the most common problem is going to be the blower motor itself, relay, or the switch panel.

You can check this by turning the fan speed to "high", unplug the blower motor, and check to see that you have roughly at least 12v at the plug. If you have 12v, that means the switch panel is activating the relay and the relay is working. Over time, heat kills the magnetic properties of the magnets inside an electrical motor. Without enough magnetic energy, you may not get enough opposing force to spin the rotor full speed when the windings energize, but still enough to spin at lower speeds.

Another thing you can check is the connector at the blower motor and the switch panel. Sometimes these will heat up, start to deform, and cause a bad connection. The bad connection may be able to handle the lower current draw on low speeds, but the higher resistance from the bad connection won't be able to handle the higher current while in the full speed position.

Hope this helps, keep me posted. be glad to help you get your heater working again soon.

its a bad ground run a ground wire form the neg side of the battery too the metal plate on the motor!!