How To Check A Bad Furnace Blower Motor (Step By Step Guide)

Bad Furnace Blower Motor is one of the most reported problems by AC owners. They always complain that their ac unit is running, but the blower motor is not turning on.

Out of all the ac repair calls I get, this is one of the most common ones. Sometimes your blower motor can be bad but sometimes other furnace assemblies can be causing the blower motor to not work properly.

In this article, I’ll list all the reasons why your blower motor has gone bad (and their DIY solutions) in hopes that you don’t have to pay for a technician’s visit. 

Inspection No #1: Check Your Blower Motor Capacitor - How To Check A Bad Furnace Blower Motor

Every furnace blower motor has a capacitor installed beside it to jump-start the motor. Sometimes that capacitor goes bad and it can cause your blower motor to not work properly.

Remember capacitors are not long-lasting components; they do die with time and you need to replace them with new ones. If your blower motor is not working the first thing to do is check your capacitor.

Your capacitor is typically going to be on the motor housing somewhere.

First, when working on any electrical item, you should make sure that it is turned off before anything else. You should turn off your furnace's power switch and the circuit breaker before working on it.

It's crucial to turn off a furnace before utilizing it for a few reasons. For one, leaving the furnace running could result in sparks that could be harmful. The materials in the furnace could catch fire if these sparks ignite them. Another reason to switch off a furnace before using it is that if you don't, you might not have enough time to escape in case of an emergency. You won't be able to flee the furnace quickly enough if there is a fire inside due to the heat and smoke. Also, there is the potential for electric shock from furnaces.

Operating the furnace while the power is on is not advisable because the results could cause bodily harm, and even have the potential to be fatal.

Next, you need to disconnect the wires from the capacitor. Then unscrew the strap that’s holding the capacitor and take your capacitor out.

After this, you need to test your capacitor rating on the multimeter. If your capacitor is not showing any reading then it is probably dead and you need to replace it. Tthat means your blower motor is likely working fine.

Inspection No #2: Check If Your Blower Motor Is Getting Power From Control Board - How To Check A Bad Furnace Blower Motor

The next thing you want to do is just verify that your blower motor is getting power from the control board. To do that you’ll need to remove the wires from the control board and check the voltage from the socket. 

If you’re checking during the AC season, follow these steps:

1. Turn off your furnace power switch and circut breaker. You should not operate your furnace while the power is flowing through it. It can be fatal so make sure to take proper precautions.

2. Pull off your cooling and common wires from the control board.

3. Put your multimeter leads into the cooling and common socket of the control board. Then check if you’re getting the proper voltage (120V). If you’re not getting any voltage then your control board is bad and the problem is likely not your blower motor.

If you want to check for the furnace season then remove the heating and common wire and test them with the same process as listed above.

If your control board is not sending power to the blower motor then you need to get it replaced or repaired.

How to Check Your Control Board if you Don’t Have a Meter - How to Check if There is Power Coming From the Control Board

In my opinion, if you own any electrical unit as big as an AC, then you should have some basic electrical equipment also. However, not everybody has a multimeter at their home. So then, how do you check your control board if you don’t have a multimeter? 

There’s one way you can do it by bypassing the control board—or in other words: hotwiring it. 

So to bypass the control board, you need to follow these steps:

Step 1: First, you should turn your furnace power switch off. You don't want to have any power running through the furnace while you’re operating the control board. 

Step 2: Then what you want to do is find your line terminal from where the power comes into the control board. You want to pull that wire off. It'll usually be coming from the door switch.

Then if you're in the furnace season, you want to pull off your heat wire. However, if you're in the AC season which we are right now you wanna pull off your cooling wire.

Step 3: Now all you're going to do is bypass the control board and send power to the blower motor directly. To do that you need to wire nut those two wires that you snip off. 

Step 4: Now if your blower motor starts by bypassing then you know that your control board is bad and you need to get it replaced. If bypassing doesn’t start your motor then your blower motor is bad and you need to get it replaced.

Furnace Blower Motor Replacement Cost - How To Check A Bad Furnace Blower Motor

A furnace Blower Motor can cost between $100 and $1900 depending on the brand and labor charges. 

Blower Motor Cost by Brand:

  • Rheem = $250 - $900

  • Carrier = $100 - $1,600

  • Trane = $175 - $1,500

  • Lennox = $150 - $1,500

  • Goodman = $75 - $800

  • York = $150 - $1,800

Blower Motor Parts Price List: