If your AC or furnace fan motor seems to be working overtime, it might be more than just a noisy inconvenience.
A fan motor that draws too much power can signal serious underlying issues, anything from worn bearings to faulty wiring.
Left unchecked, it can lead to higher energy bills, frequent circuit breaker trips, and even motor failure. But how do you tell what’s really going on?
Let’s break down how an electrical diagnosis helps get to the root of the problem.
Why Fan Motors Draw Too Much Power
Your HVAC fan motor is designed to draw a specific amount of current, which you can find on the motor’s nameplate. When it exceeds that value, something is causing extra resistance or mechanical stress. Common culprits include:
- Worn Bearings or Aging Motors: As motors age, the internal bearings and components wear down, creating friction that forces the motor to work harder. This increased effort translates directly into higher power draw.
- Mechanical Obstructions: Dust, debris, or even a misaligned fan blade can physically block movement. When the fan has to fight against that resistance, it naturally consumes more electricity.
- Faulty Wiring or Relays: Frayed wires or corroded terminals increase electrical resistance. Similarly, a faulty relay can keep the fan running continuously, causing overheating and excessive energy use.
- Low Supply Voltage: When the voltage supply drops, the motor compensates by drawing more current to maintain performance. Ironically, that effort can cause overheating and damage over time.
- Incorrect Motor Sizing: If the motor is undersized for the system, it will always run under strain. An oversized motor, on the other hand, can waste energy and damage other components.
How Electrical Diagnosis Works
A proper diagnosis starts with a visual inspection to check for debris, misaligned blades, or damaged wiring. Then, a technician measures the amp draw using a multimeter and compares it to the manufacturer’s nameplate rating.
If the current reading exceeds specifications, the next step is to inspect the wiring, connections, and relays for corrosion or damage. In some cases, a continuity test is performed on the motor windings to identify internal faults.
Since electricity and HVAC components can be dangerous, this process should always be handled by a qualified technician. Attempting to DIY a motor diagnosis could lead to electrical shock or further equipment damage..
Final Thoughts
A fan motor drawing too much power isn’t just inefficient; it’s a sign your HVAC system is struggling. The sooner you identify and fix the problem, the better you can protect your comfort and your wallet.
If your system is showing signs of electrical strain, don’t wait for a full breakdown. Call Bell Brothers today for expert electrical diagnosis, motor repair, and HVAC service to keep your home running efficiently and safely.