Fan Speed in A/C


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Old 02-25-08, 04:54 AM
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Fan Speed in A/C

what is the speed of the fans inside an A/C?

in fan speed, normal, and high speeds? (in rpm)
 
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Old 02-25-08, 05:20 AM
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Typically a motor is just rated for this high RPM and the lower speeds aren't listed. There are a wide variety of different speeds but the most common ones I see range between 1000 and 1150 RPM. The standard motor speed replacement is usually a 1075 RPM motor.

Of course there are faster and much slower ones too. If you have to replace one you will either need to pull the old one and read the data plate on the side of the motor stating RPM, Horse Power (like 1/3 HP or whatever) and the amperage wich may be listed like 2.1a or 2.1 RLA or the like.

It's a safer bet if your replacing the motor and not getting a direct factory replacement from a dealer to get the closest in RPM (say if it was a 1000 I'd get a 1075 wich is standard) and then match up by the Amperage and not worry so much about how close the horse power is.

Michael
 
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Old 02-25-08, 03:14 PM
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Wink

Most units are set for the fan on high speed for AC. A AC unit blower should run at about 400CFM per ton. Or 1200 CFM for a 3 ton AC
 
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Old 02-26-08, 04:41 AM
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does the speed vary when you set your WINDOW-TYPE AC to fan, low cool, medium cool, high cool setting? or just the amount of the refrigerant passing through the compressor?
 
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Old 02-26-08, 03:35 PM
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No window a/c fan motor that I know of advertises the RPM of each speed setting.

The different speeds slow the fan motor down which lowers the a/c's capacity which indirectly reduces the refrigerant flow throughout the system.
 
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Old 02-26-08, 07:09 PM
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Do What

That's what I said
 
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Old 02-27-08, 06:26 AM
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what do i mean is that we all know that in a typical window-type air con, there are 4 settings (fan mode, low cool, medium cool and high cool).

does changing its setting, also changes the speed of the fan's motor?

is it just the same air volumetric flow, same rpm of the motor but different temperature?

thanks sir GregH, Ed Imeduc and mike2501 for answering my queries!
 
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Old 02-27-08, 05:18 PM
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Low, medium and high cool only changes the fan speed.
While in the cool mode the compressor will cycle on/off through the thermostat.
 
 

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