What Would Cause the Blower Motor to Draw Low Amperage? Find Out!

Having poor air circulation in your home can be a really frustrating experience. Especially on the hottest summer days. No doubt that the problem is with your HVAC system. For some reason, the blower motor is drawing very low amperage.

But why?

What would cause the blower motor to draw low amperage?

It’s possible that the motor is running below the rated load due to low amperage. Obstruction in the volute can make the amperage low. Obstacles stuck in the blower fan can be yet another reason for that. And that can also cause low amperage. Good thing is that these issues are easily fixable.

So, let’s take a deep look into the article and fix the low amperage issue. 

Blower Motor Drawing Low Amperage: Reason And Solution

We are talking about drawing a lower amp on the blower motor. So, you should know what should be the perfect amp. The amperage of a gadget indicates how much electricity it consumes. On the name tag of the motor, the amps will be indicated.

Generally, It’s possible to get up to 20 amps or more for the blower. If it’s less than 20 then you got to know that your blower motor is drawing low amperage. 

The current is reduced by rising the voltage. As power travels over the wires, the reduced current associated with high voltage transmission lowers conductor resistance. Long-distance transmission may now be accomplished using thin, lightweight cables.

Source: homeguide.com

In general, there are 4 reasons that can cause low amps in motors. These reasons can also lead to a low-pressure lockout. Let’s go through them one by one:

Reason 1: Motor Running Below the Rated Load

It’s possible that the motor is not operating at full load. This makes the motor less efficient since it’s not supplying the rated power it’s designed to produce.

We’d anticipate all those meters to read low. That is if the voltage waveforms to the motor were severely skewed for some reason.

Solution: Check and Reset the Limit

Check that the voltage applied matches the nameplate. If this occurs, double-check that the motor and drive are turning freely. If your 3-phase motor pulls low amps.

The motor’s horsepower may need to be raised. And that is if the voltage to the motor looks good and the drive system operates easily. Examine the power source for the possibility of boosting the horsepower rating by one.

If you aren’t sure how to check blower motor amp draw then there are lots of tutorials about that. 

Reason 2: Motor Runs at a Higher voltage

When the motor is driven at a voltage greater than its rated limit, the current drawn is reduced. It can create problems like lessening the efficiency and heating up the motor.

Solution: Reduce Voltage as Required

Make that the voltage applied corresponds to the nameplate. Check that the motor and drive are rotating freely if this happens.

The voltage to the motor appears to be good and the drive system runs smoothly? Then the motor’s horsepower may need to be decreased. Test the power source to see if you can reduce the horsepower rating by one.

Reason 3: Obstruction in the Volute

When there is a blockage in the volute, electric motor-driven pumps require more current. That prevents the impeller from spinning freely, or when a bearing breaks. Because the fluid is just spun.

When the input or discharge is blocked, the pump draws less current. See if the discharge line has become disconnected or not. The current will then reduce due to the lack of head pressure.

Solution: Clean the Volute

If you find obstacles in the volute you need to clean it asap. There can be dirt or another kind of objects like leaves or hair. There can also be other dead insects.

So, find out what is the object that makes the obstruction. Clean it as per required. You can try these techniques to clean your blower motor. 

Source: pinterest.com

Reason 4: Fan Blades Are Stuck

Similar symptoms might be seen in an air handler. The drive motor will need greater current. That is if the fan blades are not free to rotate or the bearings are deteriorating. 

The motor will draw less current than usual. That is if the blades are not correctly fastened to the spinning shaft. And owing to a sliding connection or a damaged drive belt.

Solution: Fix the Fan Blades

Generally, fan blades can get stuck because of obstruction in the blower. There can be different types of objects like dirt or dead small animals like mice or cockroaches. You need to clean those up quickly.

The fan blades can also be bent because of those objects. You may solve the problem by removing the fan. If it’s not fixable then you just need to replace the fan. 

But what if you find the blower is completely broken! Well, in that case, you need to get it replaced with a new one. But the cold liquid line can also create problems in cooling your house which is fixable.

To avoid replacing the blower motor often, you should replace them with quality blower motors. And we got just the right recommendations for you! Have a look at these durable, high-quality blower motors:

Try these replacement blower motors for your furnace for a change. These last for very long time and is very much tolerant to overheating. 

What Will Happen if Your Blower Motor Is Drawing Low Amperage!

What if the shaft load is less than the rated load? The motor is connected to its rated supply voltages. The motor is also drawing less current than it is rated for. What occurs?

• The induction motor’s slip will be less than its rated value.
• Losses will be reduced, as will heating costs.
• The effectiveness of the blower motor will be reduced.
• There may be reduced noise, vibration, and stress on the shaft.
• It’s possible that the power factor will be lower.

At the first glance, these symptoms may not look like a big deal. But they can affect the efficiency of your thermostat. So you should find what causes a motor to draw lower than normal amps right! 

FAQs

How Do You Check a Motor Short Circuit?

You should check the windings for a “short to ground” in the circuit, as well as any open or shorts. To check for a short-to-earth in your motor, set your multimeter to ohms. Unplug the motor from the power supply. Then glance over each wire for endless readings.

Why Do Motors Burn at Low Voltage?

Low voltage forces a motor to draw more current in order to produce the power required. Which causes the motor windings to overheat. The rule of thumb for motors is that “motor life is reduced by 50% for every 50 degrees F. And a motor is run over its rated temperature.”

How Do You Improve Low Voltage?

A transformer might be used to raise the voltage in your home. To manage the current, 100 or 200 Amp service, would be rather enormous. And be pricey, requiring the services of a qualified electrician. The transformer would have taps to allow for minor increments.

EndNote

Hope you got the answer to what would cause the blower motor to draw low amperage! 

If there are any more queries please drop them in the comment section. 

Till then have a safe and healthy life. 

Tim David

HVAC tech with over 30 years of experience. Retired and doing repair work on the side around Madison County, AL.