Central air conditioner fan Two Fan Motor in Central Ac Unit
Central Air Conditioner Fan
All residential central air conditioner units will have two fan motor. These motor are:
Blower motor
Condenser unit motor
Blower motor aka indoor blower
The blower motor is located inside a house in split central air conditioning unit. If its package unit, it’s located outside with other.
What does it do?
The blower or fan is a device that produces airflow or air movement. It provides the pressure difference to force the air into the duct work and through the supply vents.
The amount of airflow it provides is depending on the amount of airflow it receives. For example, a dirty filter is blocking airflow to the blower, what happen? It didn’t receive adequate airflow, so it produces less airflow.
There are other things that affect the airflow. Like the conditioner of the motor, the wheel and the housing. That is why; some technician recommends you clean the indoor blower.
It’s always good idea to clean it. The evaporator coil provides the cool air and the blower move these air. Without a clean blade, it doesn’t quite work at it max. It’s wasting energy.
Some central air conditioning units will have different blower speed for heating and cooling air. It takes more energy to move cold air than hot air. So, it will have different speed for it.
There are four parts to blower:
The motor
The wheel
Belly band mount
The housing
The blower’s motor and it features
Electrical Wire Diagram
All air conditioner fans motor will have an electrical wire diagram sticker on it. Here is information you will be seen on the motor diagram.
The horsepower of the air conditioner fan range from 1/8 to ¾ (1/8, 1/6, 1/5, ¼, 1/3, ½, 1)
Voltage
The residential voltage on most motor is 208-230. One of the motor wires will going to L1 or L2, it should have that on the wires diagram.
Multiple speeds
Some motor will have multiple speed, it speeds will be High, medium, medium low and low. There will be a diagram on the motor telling you what color wire is for what speed.
Rotation
Most air conditioner fan is reversible. It could rotate clockwise (CW) and counter clock wise (CCW). There should be label and reversible wire on the motor.
Speed (R.P.M)
R.P.M or revelations per minute for the motors are range from 1200 to 1050. This information is also on the motor’s label.
Amps (current)
The air conditioner motor should have AMPS label on the motor. It should have amps range from 1.0, 1.4, 1.8 etc.
Capacitor
The blower’s capacitor is a run capacitor. The motor will have brown with white stripe and solid brown wire attack to the capacitor. (Sometime there will just be two solid brown wires from the motor).
It capacitor are in the range of 5 to 7.5 MFD (microfarad) or UF. The capacitor has a round or oval shape.
Here is Capacitor Video by DrZarkloff
The blower’s wheel
The motor’s shaft is attached to the wheel. The wheel causes the airflow. If the wheel is dirty and messing, it will causes the motor to work extra hard.
It always good ideas to clean the wheel every years (depend how dirty you house is and how often you change the filter).
The Belly band mount
The belly band is a strap that wraps around the motor to secure it. You will see another brackets screw to the strap.
The purpose of the belly band is to secure the motor into the house. There are different types of strap that often used in motor, but belly band is most common.
The housing
The housing is what holds the motor and the wheel together. The belly band screw into the housing and it hold the motor there.
The housing is a venturi that allows airflow in straight line from one side of the fan to the other side. Air conditioner fan pulls in low pressure air from one side and forces it into high pressure air.
The force that moves the low pressure air into the high pressure is centrifugal force.
Condenser unit motor (fan)
The condenser unit rejects the heat from the evaporator coils, and the condenser fan helps with removing that heat.
The features of the condenser fan motors are quite the same as the blower motor. Except the condenser fan does not have wheel or housing. It has the motor and the fan’s blade.
Some split-central air conditioning unit will have dual capacitor for the compressor and the condenser fan. Dual capacitor is capacitor that does two things.
Watch for condenser airflow
Experiences and school taught us that the airflow to a condenser unit supposed to be upward. The fan supposed to reject the heat upward and not downward.
I had work on central air conditioner units and the entire neighbors have the airflow downward. What is their reason for that? Not sure.
Airflow upward is efficient and logical to me. Here is my reason for that. Over the year, leaves, debris and dirty tend to be inside the condenser units. If the air conditioner fan were to force air downward, it would force the foreign material into the aluminum coil and trap it there.
It’s logical and efficient for the condenser fan to suck in the air from the surround condenser area and force it upward.
If your condenser fan is force air downward, ask your technician for his reason. If he thing it proper to have it flow upward, he could always reverse the rotation of the fan.
