Buildup of dust, dirt, or debris. Electrical problems, including an excessive voltage supply. Motor insulation failing prematurely due to high temperatures. A weak blower capacitor.
Overheating is one of the most frequent occurrences that can render the blower motor inoperative. If the motor has overheated, it may shut itself down to prevent damage. You should keep your HVAC clean and clear of any blockages or debris to avoid overheating and maintain efficiency.
If the blower isn't turning on at all, this is a symptom that can indicate a full replacement motor is necessary. Other problems that can cause this symptom are a faulty relay, bad thermostat, or problem with the unit's fan control. Each of these issues should be diagnosed and repaired by an HVAC technician.
A defective ground wire or ground wire connection and an open circuit in the power-side circuit (including the fuse, wiring, and fan switch) are the most common reasons why a blower motor fails.
When you have NO speeds, it's probably the motor, but could be the blower speed switch or fuse. Check the fuse and test for voltage at the motor, and replace the motor if it's getting power but won't spin.
Some of the reasons a blower motor might fail are overheating, and excessive moisture. When dust, dirt, and debris build up, it can cause the windings and bearings to burn up more quickly.
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.
If your motor's electrics and bearings are constantly exposed to too much heat, then they will begin to fail. If you let your motor overheat repeatedly and fail, then either a component has broken or a bearing has seized.To prevent overheating, check your vents, filters, and in-room airflow.
On some platforms, a faulty blower motor relay will cause the blower not to work at all, which means there will be no airflow from the A/C. On others, the blower won't work on “high blow” but all the other speeds will work. The blower motor relay fails because it regularly deals with high current loads.
The replacement of the blower motor is common and straightforward, so most shops will perform the repair — many on the same day.
Blower motors are designed to last just as long as your furnace itself, anywhere from 10 to 20 years. Just as with any HVAC system, the better maintained and serviced your equipment is by experienced HVAC technicians the longer it will last and the fewer repairs you'll face.
1) A Bad Fuse
The most common reason why your blower motor won't work on any speed is that you have a bad or blown a fuse. A fuse is a small wire inside of a connector that is used to protect the motor itself from a surge of electricity.
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.
If the blower is slowed down enough or the downstream pressure rises suddenly beyond the capacity of the blower surge will occur. Because the pressure downstream is now greater than the capacity of the blower, the air will now reverse and try to flow back into the blower.
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.
The top reason that blower motors fail is because a heating and cooling system has restricted air flow, something we call “high static pressure.” There are many reasons this can occur. Air flow can be restricted when air filters are exceptionally dirty and rarely if ever replaced.
If the cooling fan relay has failed, you may see warnings, such as the check engine light and the temperature warning light, pop up on the dash, but first, you may notice that the A/C stops cooling. More about that in the next paragraph. The check engine light illuminating may indicate a faulty cooling fan relay.
Strange Rattling, Clanking, or Screeching
One of the first signs you may notice when there's an issue with the blower motor is a strange noise coming from the indoor unit or air handler.
There are several things that could cause a blower fan to burn out, and most of them are related to wear and tear on the component. Causes of blower fan burnout include: Windings that have deteriorated. Bearings that have seized after running out of oil.
Typically, the lifespan of furnace blower motors spans from a minimum of 10 years up to about 20 years, with most enduring an average period between 15 and 20 years. The same blower motor is used for both heating in the winter and cooling in the summer, making it essential for maintaining indoor climate control.
A blower motor should last at least 10 years, and could last up to 20, depending on the type of HVAC unit you have in your home. There are a few warning signs that your blower motor is damaged, including little-to-no airflow coming from your vents, a burning smell, and skyrocketing energy bills.
Replacing the blower motor is likely the best decision if your furnace is under warranty or relatively new. It might be better to replace the furnace if it's old or has a lot of issues that require frequent repairs.
More specifically, systems that include blower motors have a lifespan of roughly: Air-Source Heat Pumps: 10 to 12 years, with a maximum of 15 years or more. Furnaces: 10 to 20 years, depending on maintenance schedules. DX Air Conditioners: 15 to 20 years, depending on maintenance schedules and manufacturer quality.