Trane A/C Unit TWR042C100B1

[Betsy]

I seek wisdom from the Samurai...

Just spent a bundle 3 months ago on a new condensor fan motor. Noticed a crack in one of the fan blades. Is replacing the fan blade easy? Looks like a few bolts and it should slide off then I can put the new one on.

Is there something more I should know about...like adjustment for balance? Any enlightenment you can provide will be appreciated.

 

 

[dkpd1581]

It can be as easy as removing one or two set screws and pulling the blade off.  New blades come balanced from the manufacturer.  Typically I change the blade at the same time as the new motor is installed for just the reason you have written - cracked blade. 

The new motors tend to start with more torque than the older motor.  Old blades usually will crack due to metal fatigue from years of exposure, higher start torque of the new motor, and they may become unbalanced over the years.

My Company's policy is to change the blade at the same time.  Yes it costs more; however, it prevents this problem, call backs, loss of service, and helps ensure a higher quality of overall workmanship.

You can gently sand the exposed end of the shaft if necessary, remove the two set screws, spray some WD40 or other penetrating oil into the screw holes and shaft.  Allow it a few mins to do its job and then gently/evenly pull the blade off.  In cases of stuborn blades, a Posi-lock puller or gear puller equivalent may be necessary - DO NOT BEAT OR PRY THE OLD BLADE OFF YOU WILL DAMAGE THE SHAFT.

Since this one was presumably just replaced it should come off easily. Just measure how much of the shaft protrudes below the blade's hub so that you can put the new one on at the level.  You can also look through the screw holes of the new hub and line then up with the marks left on the flat surfaces of the shaft by the old one and be relatively close.  Blades ARE directional so make sure you put the new one on with the petals in the same direction as the old one.  Be certain that your new blade has the correct bore diameter petals numbers and pitch.

The following may create controversy; however, if possible GET NEW BLADE ASSEMBLY FROM THE MANUFACTURER.  Generic blades can have different numbers of petals and  slightly different pitches (while moving the same amount of air), but most importantly is the weight issue.

Generic blades tend to be heavier than OEM,  Generic blades tend to be sold with a seperate hub that has to be installed in addition to and before installing the blade to the shaft.  The sum total of this weight/configuration difference may cause you to have to go to a slightly different sized motor to adequately spin it.  Motors are designed for specific airflow requirements, generating specific horsepowers, at specific RPMS, under specific conditions, able to generate specific torques.  Going with an OEM part helps ensure all of the above and helps guarentee the service and longevity of the device.  Many premature failures of motors happen when someone carelessly puts motor to blade/wheel (Oh this will do just fine) without giving consideration to these factors. 

My best advice - go OEM.

Best of luck.

[Betsy]

Already have the blade from the manufacturer. Info you provided was very helpful. As you mentioned there are set screws so it should go smoothly. (Famous last words:))

Thanks for the help...I'll post again later on how it all goes.