Does the blower motor resistor have anything to do with the AC?

Author: Elyssa Mitchell  |  Last update: Wednesday, March 4, 2026

Since it directly contributes to airflow, a bad blower motor resistor will affect your HVAC system's ability to both heat up AND cool down. If your fan seems to work properly, the speed settings function, and air is moving fine, but it's just not getting cold, then you may have a bad heater core.

Does the blower motor resistor control AC?

Usually, it's a compact, rectangular device with many resistors of varying resistance integrated into it. This component's main job is to control the blower motor's speed, which in turn manages the HVAC system's fan speed.

Can a bad blower motor resistor cause no AC?

Best Answer If the resistor block has failed, you will only have high speed from the blower. The blower and the compressor are two separate circuits. No, one won't effect the other unless there's something catastrophic like a severely melted blower speed switch. You'd probably smell that one.

Does a blower motor affect AC?

A blower motor is the part of an AC or furnace that controls the amount of air pushed through the air handler. A motor's performance can largely affect air conditioners' functionality in meeting industry standards. Blower motors typically come in two types – single-speed blower motors and multi-speed blower motors.

How do you diagnose a bad AC blower motor?

6 Signs of a Bad AC Blower Motor
  1. Weak Airflow From Your Vents. One of the first signs you may notice is what feels like less air coming from your vents. ...
  2. No Airflow. ...
  3. Unusual and Loud Sounds. ...
  4. Climbing Utility Bills. ...
  5. Overheating. ...
  6. Tripping Circuit Breaker.

Heat Stopped Working In My Car! Blower Motor or Resistor?

Will a blower motor work without the resistor?

The blower motor can indeed function without the resistor. As we know, the resistor is responsible for controlling the blower motor's speed by regulating the voltage supplied to it. It will turn out that without the resistor, the blower motor may run at maximum speed or not function as expected.

How much does it cost to replace a blower motor on an AC unit?

The average blower motor replacement cost is $560, but the final price depends on labor fees, as well as the cost of the parts. Some higher-end models feature large or hard-to-reach motors, which could bring your HVAC blower replacement cost to as much as $2,400.

Can the blower motor stop AC from working?

However, they can eventually burn out, so if your AC unit's blower motor is old, it might be time for a new one. One sign of a faulty blower motor is an air conditioner that still runs without blowing cool air. Remember: If the blower motor stops working, air is not moving through the system.

How do I know if I need a new AC blower motor?

7 SIGNS YOU NEED A NEW AC MOTOR
  • AC Fan Doesn't Start. If you have a bad AC fan motor, you may have problems with your AC fan starting in the first place. ...
  • Overheating of the Air Conditioner Fan. As a blower motor ages, it can start to overheat. ...
  • Weird Sounds. ...
  • Higher Energy Bills Than Normal. ...
  • Weak Airflow From the Vents.

How much does it cost to replace a blower motor resistor?

The average cost for a Blower Motor Resistor Replacement is between $119 and $154. Labor costs are estimated between $43 and $54 while parts are priced between $76 and $99. This range does not include taxes and fees, and does not factor in your unique location. Related repairs may also be needed.

Which of the following is a common symptom of faulty blower motor?

Strange Rattling, Clanking, or Screeching

One of the first signs you may notice when there's an issue with the blower motor is a strange noise coming from the indoor unit or air handler.

What causes blower motor resistor to fail?

Causes of blower motor resistance failure

Corrosion can destroy electrical connections and prevent the resistor from functioning properly. Electrical Overloads: Sudden voltage spikes, overcurrent conditions, or electrical faults in the system can place excessive electrical stress on the blower motor resistors.

Can a bad blower motor cause no AC?

The AC system is responsible for circulating air through the system and into your home. Therefore, if you notice that there is low or no airflow from your vents, it's an indication there may be a problem with your blower motor that needs repair or replacement by a professional.

How do I know if my cooling fan resistor is bad?

What common symptoms indicate you may need to replace the Cooling Fan Resistor?
  1. Cooling fan never stops running even with the ignition off.
  2. Cooling fan never kicks in and engine temperature increases abnormally.

What controls an AC blower motor?

The blower motor resistor is responsible for controlling the blower motor speed. In the past, this was done by varying the voltage supplied to the blower motor.

Will low freon cause a blower motor not to work?

If the indoor blower fan has malfunctioned, cold temperatures outside the home, or low refrigerant charge, the evaporator coil can freeze. If this happens, call your local Trane expert for professional assistance.

Why does my AC in my car only work on high?

The blower motor resistor is prone to shorts, corrosion, and overheating. When the resistor fails, typically, the highest setting is the only option that still functions. This is because the air from the blower motor is bypassing the resistor, thus gaining the maximum amount of voltage, resulting in full power.

Why is my central AC running but not blowing air?

If your air handler is running but not blowing air, there are two likely scenarios: either a broken AC blower belt or an issue with the motor itself. If the air handler is humming or buzzing but not making the mechanical sounds of a motor running, you're most likely talking about an issue with the motor itself.

What is the life expectancy of an AC blower motor?

Blower motors are designed to last just as long as your furnace itself, anywhere from 10 to 20 years. Just as with any HVAC system, the better maintained and serviced your equipment is by experienced HVAC technicians the longer it will last and the fewer repairs you'll face.

How long does it take to replace a blower motor on an AC unit?

It typically takes one to four hours for the technician to replace the AC fan motor. Normally, good technicians will check for other issues during this replacement. If more problems are found, they will be repaired as well.

Is a blower motor easy to fix?

The replacement of the blower motor is common and straightforward, so most shops will perform the repair — many on the same day.

What happens if blower resistor goes out?

The blower motor resistor controls the power to the system's blower motor. When it fails, it can cut off all power to the motor. When the blower motor doesn't get power, air pressure can't be produced. You are left with a heater or air conditioner with nothing coming out of the vents.

Why is my AC not blowing air in my car?

The blower motor is responsible for pushing air through the vents inside your car. So if you have absolutely no airflow coming through your vents, it's possible that your blower motor or the resistor that controls its speed has failed.

What does the blower motor resistor connect to?

A blower fan is connected to the negative battery terminal (also called ground) on one end and to the positive battery terminal through a blower resistor on the other end. The blower resistor is connected in series with the blower fan.

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