Troubleshooting High Amp Draw in Blower Motors: Causes and Solutions

Blower motors are crucial components in various heating, ventilation, and air conditioning (HVAC) systems, responsible for circulating air throughout a space.

It is essential for blower motors to draw the appropriate amount of electrical current, known as amps, to ensure efficient operation.

However, there are instances when blower motors draw high amps, indicating an underlying problem that needs attention. High amp draw in blower motors can be caused by various factors such as restricted airflow, motor overload, electrical issues, motor winding problems, and faulty capacitors.

In this article, we will explore the possible causes of high amp draw in blower motors, its consequences, and troubleshooting solutions.

Understanding Blower Motors

Blower motors are integral to HVAC systems, providing the necessary airflow for heating, cooling, and ventilation.

They consist of several components, including the motor itself, fan blades, bearings, and electrical connections.

The motor converts electrical energy into mechanical energy to drive the fan and circulate air.

Normal Amp Draw for Blower Motors

Blower motors have a typical range of amp draw that manufacturers specify. This range can vary depending on the motor’s size, design, and intended application.

However, most blower motors generally draw between 5 to 20 amps during normal operation. It’s important to note that specific models may have different amp draw requirements, so consulting the manufacturer’s specifications is essential.

Causes of High Amp Draw in Blower Motors

Several factors can contribute to a blower motor drawing high amps, indicating an underlying issue. Let’s explore some of the common causes:

Restricted Airflow

  1. Clogged air filters: Accumulated dust, dirt, and debris can obstruct air filters, leading to reduced airflow and increased resistance, causing the blower motor to work harder and draw higher amps.
  2. Blocked vents or ductwork: Obstructions in the vents or ductwork can impede the smooth flow of air, creating additional strain on the blower motor and resulting in high amp draw.
  3. Damaged or obstructed blower fan blades: Bent or damaged blades or foreign objects obstructing the fan can disrupt airflow, causing the blower motor to draw more current to compensate.

Motor Overload

  1. Excessive load on the motor: Overworking the blower motor by setting it to high speeds continuously or using it beyond its capacity can cause it to draw higher amps.
  2. Binding or mechanical resistance: Mechanical obstructions, such as misaligned or stuck components, can impede the motor’s rotation, increasing the amp draw.
  3. Faulty motor bearings: Worn-out or damaged motor bearings can create friction, leading to increased resistance and higher amp draw.

Electrical Issues

  1. Voltage fluctuations: Inconsistent voltage supply can cause the blower motor to draw higher amps than necessary.
  2. Loose or corroded electrical connections: Poor connections between wires or terminals can increase resistance and result in high amp draw.
  3. Short circuits or electrical grounding problems: Faulty wiring or grounding issues can cause electrical imbalances, leading to the increased current drawn by the blower motor.

Read also my article: Understanding Ceiling Fan Motor Overamping: Causes and Solutions

Motor Winding Problems

  1. Burned or damaged windings: Overheating, electrical issues, or age-related wear can damage the motor windings, affecting its efficiency and causing it to draw more amps.
  2. Insufficient lubrication: Lack of proper lubrication in the motor bearings can increase friction, resulting in higher amp draw.
  3. Overheating of the motor: Excessive heat buildup due to inadequate cooling or prolonged operation can impact the motor‘s performance, leading to high amp draw.

Faulty Motor Capacitor

  1. Defective or failed capacitor: The motor capacitor helps provide the initial electrical boost to start the motor. A faulty or failed capacitor can hinder the motor’s operation and increase amp draw.
  2. Capacitor with incorrect specifications: Using a capacitor with incorrect ratings or specifications can cause the blower motor to draw higher amps than intended.

Other Potential Causes

  1. Motor age and wear: Over time, blower motors can experience wear and tear, which can impact their efficiency and increase amp draw.
  2. Improper blower motor size: Installing a blower motor that is either too small or too large for the system’s requirements can lead to high amp draw and inefficiency.
  3. Environmental factors: Extreme heat or adverse environmental conditions can strain the blower motor, causing it to draw more current.

Detecting High Amp Draw in Blower Motors

Recognizing the signs of high amp draw in blower motors is crucial for timely intervention. Some indicators include:

  • Blown fuses or tripped circuit breakers.
  • Unusual humming or buzzing sounds from the motor.
  • Hot motor or excessive heat near the motor.
  • Decreased airflow from vents.
  • Increased energy consumption.

Using a multimeter, a device that measures electrical current, can help quantify the amp draw accurately. However, it is recommended to seek professional inspection and diagnosis for accurate assessment and safety.

Consequences of High Amp Draw

High amp draw in blower motors can have several negative consequences, including:

  1. Reduced blower motor efficiency: Excessive amp draw indicates that the motor is working harder than necessary, reducing its overall efficiency.
  2. Increased energy consumption: The higher the amp draw, the more electricity the blower motor consumes, resulting in increased energy costs.
  3. Potential damage to the blower motor or other components: Continuous high amp draw can put strain on the motor and other HVAC components, potentially causing premature wear and failure.

Troubleshooting and Solutions

To address high amp draw in blower motors, the following troubleshooting steps and solutions are recommended:

  1. Regular maintenance and cleaning: Routinely clean or replace air filters, remove obstructions from vents or ductwork, and ensure proper lubrication of motor bearings.
  2. Airflow optimization: Check for and rectify any mechanical obstructions, ensure the blower fan blades are undamaged, and maintain proper airflow throughout the system.
  3. Motor and electrical system inspections: Inspect and tighten electrical connections, check for voltage fluctuations, and assess motor windings for damage.
  4. Capacitor replacement: If the capacitor is suspected to be faulty or failed, consult a professional technician to replace it with the appropriate specifications.
  5. Professional repair or replacement options: In severe cases or when troubleshooting efforts fail, it is advisable to seek professional assistance for repair or replacement of the blower motor or related components.


Maintaining a blower motor’s optimal amp draw is crucial for the efficient operation of HVAC systems. High amp draw can be caused by various factors such as restricted airflow, motor overload, electrical issues, motor winding problems, faulty capacitors, or other underlying issues.

Recognizing the signs, detecting high amp draw accurately, and addressing the root causes promptly can help prevent further damage, improve energy efficiency, and extend the lifespan of the blower motor.

Regular maintenance, professional inspections, and appropriate troubleshooting solutions are essential in maintaining a properly functioning blower motor