Choosing a replacement motor for your heating or cooling system is easier than you think. This technique is usually followed to use a universal style motor than it is using an exact manufacturer replacement.  The advantages of using a universal style replacement is the cost.OEM motors are usually very expensive and hard to get in some cases.  Older systems manufacturer motors can be obsolete and the process for choosing a replacement is the same. 

Step 1
Is the unit a gas furnace or heat pump? 
Remember a heat pump has a 2 parts - the outside heat pump and the inside air handler.

Step 2
Choose a category from below.
Gas furnaces - Blower motor 115 Volt
Air Handler - Blower motor 230 Volt
Heat Pump - Condenser Motor 230 Volt
A/C Conditioner - Condenser Motor 230 Volt

Step 3
What is the Hp or horse power rating? - Look on the existing motor tag for the information. 
Some universal motor have a range of horse powers. 

Step 4
What is the speed? -Look on the existing motor for the information.
A mult-speed motor will only have the highest RPM rating labeled on it.
It is common for motors in furnaces to have 1 to 4 speeds with each of the lower speeds running a lower RPM.

Step 5
Frame Size - Look on the existing motor for the information.
The frame size is the motor physical dimensions and every motor has an assigned frame size.

Most residential HVAC systems use the following frame sizes

42 - Used mostly on ac and heat pump condenser fan motors
48 - Most commonly used frame size for blower and condenser motors
56 - not so common

Step 6
What is the shaft size? Usually 1/2" diameter.

Step 7
How many speeds does my motor have?  Look at the electrical tag on the motor to find out.
These are the most commonly used. 
Common
High Speed
Medium High
Medium
Medium Low
Low

If the tag is missing or unreadable, then count the wires going to the motor. 
5 wires = 4 speed
4 wires = 3 speed
3 wires = 2 speed
2 wires = 1 speed

Step 8
What direction does the motor turn?  CCW or CW (counter clockwise or clock wise)
This can be confusing if you do not know from what end of the motor to look.  Face the shaft away from you and rotate the fan in the proper direction.   If is is CCW, then the direction is CCWLE and CWLE for clockwise direction.  Universal style motors have an option to reverse the direction of rotation so rotation is not a worry.

Step 9
How is the current motor mounted?
1.   Belly Band  - The motor has what is known as a belly band around it with mounts that screw or bolt to the blower fan housing.
2.  Mounts of Ear mounts - are a permanent part of the motor that screw or bolt to the blower fan housing.
3. Independent Mounts - The mounts attached to the side of the motor and then screw or bolt to the blower fan housing - very common for Rudd & Rheem models
4.  Flex Mount - the motor has a frame that mounts around the entire motor - very common for Trane and American Standard models.
5.  Stud Mounts - The motor is mounted using threaded studs that are part of the motor - most condenser fan motors are mounted this way.

You can replace the belly band, ear mounts, and flex mounts with the a universal belly band mounting kit.

You now have enough information to choose a replacement motor. Give us a call with your info.