What controls AC blower motor?

Author: Prof. Stewart Turner  |  Last update: Friday, March 14, 2025

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.

How do I know if my blower control module is bad?

  1. Symptoms of a Bad Blower Motor Control Module.
  2. A blower motor control module is crucial for your vehicle's HVAC system. ...
  3. * No Airflow or Weak Airflow.
  4. One of the most telling signs is if the blower motor isn't blowing air at all or the airflow is weaker than usual. ...
  5. * Intermittent Operation.

What tells the blower motor to turn on?

The thermostat is what tells these separate systems to work together. In normal operation, when your thermostat is set to "auto," it will tell the blower fan plus the heating or cooling components to turn on and off at the same time when the desired temperature is reached.

Why is the blower on my AC not working?

In short, common issues that can cause an air conditioning unit fan to stop spinning are electrical issues, problems with the capacitor, contactor issues, a burnt out air conditioner motor, a broken fan belt, or clogged air filter.

How do you reset an AC blower motor?

Most blower motors are controlled by a red or black switch on the side of the unit. Hold the button down for a few seconds (the manual will tell you precisely how long), then release. Replace the Panel and Restore Power.

The Secret To Control Ac Fan Blower Motor Rotation

Can I run my AC with a bad blower motor?

Your AC's blower motor is responsible for moving air through your air conditioner to cool it and then pushing it back out into your home. Without this incredible component, your AC can't provide any cooling effect, no matter how much the compressor runs.

How to tell if it's the blower motor or resistor?

Blower Motor Resistor Test

Typically, if the fan will work on some speeds but not on others, the resistor is suspect. Okay, let's say there's no melting going on, but your fan doesn't work on all speeds. Typically, if the fan will work on some speeds but not on others, the resistor is suspect.

How do I know if my blower relay is bad?

Symptoms of a Bad Blower Motor Relay

On platforms where the blower is directly controlled by the switch rather than a module, the relay will cause the blower not to work at all, which means there will be no airflow across the evaporator, and the effect will be the same as the A/C not working at all.

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.

What part controls the 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. In newer applications, the blower motor resistor is actually a solid state module that sends a varied signal to the blower motor.

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.

Where is the reset button on an AC unit?

Power down your AC: Turn off your AC unit and unplug it from the power source. This will ensure that you stay safe while working on the unit. Locate the reset button: Most air conditioning units have a reset button located near the outside unit. It is usually a small button located inside a small hole.

What are the symptoms of a bad HVAC control module?

Since the module regulates the entire AC system, inconsistent cooling, out-of-date software, and uneven air distribution are typical signs of a broken AC control module.

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 do you diagnose a blower motor problem?

Look for these key indicators that you have a bad blower motor.
  1. Strange Rattling, Clanking, or Screeching. ...
  2. Weak or No Airflow From The Vents. ...
  3. A Sudden Spike in Your Energy Bills. ...
  4. An Overheating HVAC System. ...
  5. Replace or Maintain a Part in the Blower Motor. ...
  6. Replacing the Blower Motor. ...
  7. Keep Up With HVAC Maintenance.

What happens when a cooling fan relay goes out?

Electrical Issues ⚡️: A faulty relay can cause electrical problems. You might experience blown fuses or issues with other components connected to the cooling system.

How much does it cost to replace a blower motor?

Replacing a furnace blower motor costs $560, on average. Depending on the size and type of motor, most people pay $300 to $900. The average blower motor replacement cost is $560, but the final price depends on labor fees, as well as the cost of the parts.

How to reset blower motor?

How Do I Reset the Blower?
  1. Turn off the circuit breaker powering your HVAC system.
  2. Unscrew the blower cover.
  3. Give the blower time to cool down completely before proceeding.
  4. Push the reset button (typically a red button behind the blower motor).

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 AC blower motor is out?

If the motor is making rattling, clanking, or banging sounds, it may be because of a loose or broken part inside the system. Loud banging sounds are especially worrisome. They're usually a sign that something within the system is damaged or disconnected, potentially indicating the need to replace 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 wont the fan kick on my AC unit?

2. Breaker or Thermostat Issues. If your AC fan isn't spinning, it's possible that the issue is as simple as a circuit breaker being tripped or your thermostat not being turned on. When an HVAC technician attempts to diagnose fan problems, they will first check to make sure that power is being delivered to the unit.

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