L86 Install racks have 3 squirrel cage fans installed in each chassis. The fans have been know to fail or seize after long periods of use. Symptoms will be no air flow in a section of the rack, loud squealing noises, or worn bearing sounds.
If an end-user wishes to replace one, the task can be somewhat difficult depending on the fan housing. Some fan housings permitted replacing the internal fan motor, replacing the internal fan motor is somewhat easy. Other fan housings did not permit replacing the fan motor, replacing the fan housing can be very challenging. There are wiring differences to the fans depending on whether the rack was opto isolated. If the rack was not opto isolated, the fans ran off one cube common to all EM64s. Racks that were opto isolated; the fans ran off individual cubes per phase. So with the variances in the racks, there is no cookbook method on how to replace a fan. The end user will need to purchase a new fan and make modifications as needed. ETC highly recommends using a Contract Service Center that has worked on L86 racks in the past.
How to replace an internal fan motor, that matches the fan housing
- Turn [Off] all rack power
- Unload all the dimmer modules in the affected chassis.
- Cut the tywrap holding the wiring harness in place on the fan(s) to be replaced.
- Loosen and remove the three nuts holding the motor and squirrel cage in the fan housing
Note: Removing the screws from the back can be challenging depending on the type of nut. (captive nuts, tinnerman nuts, nuts
- Pull the motor/fan out of the housing.
- Clip the wires as close to the motor as possible.
- Replace the motor.
Note: The fan manufacturer changed bushing sizes from time to time. Usually you could swap the rubber grommets, sleeves or standoffs to make the motor fit on the studs in the housing
- Use inline splices to connect the new motor leads to the old wiring harness.
Note: Figure the length of the motor leads before you trim them so when you tyrap the leads the inline splices don't catch on the bottom dimmer module
- Replace and tighten the three nuts.
- Tywrap the wiring harness back in place.
- Since you've got the chassis open, perform a visual and finger check on all hardware and connections. Tighten any loose lugs/hardware.
- Power up and check for proper fan operation **Safety-Customer or tech exposed to power**
- Repopulate the chassis with dimmer modules (again visual / finger check)
*This can be done on a front access chassis without removing the back panels
*How to replace an internal fan motor, that does not match the fan housing
IF the replacement motor DOESN'T match the failed motor, the fan housing will need modification or replaced. Expect a longer period of time to perform this task, since it will require drills, taps, saws, and a cutting torch. You may need to remove the existing fan housing and replace it with the new fan housing. The fan housings are hard to get out and in a bussed front access rack with 1.2k dimmer modules.
Customers may find that identifying and removing the load wiring in the bay will allow for more finger access. Also the edges of the rack can be very sharp--bring lots of band aids.
Replacing Fan bushings or grommets
Endusers can order replacement grommets or bushings directly from the manufacturer.
The grommets sit on the stud housing, which is a 8-32 threaded stud that is welded to the fan housing.
If enduser is looking to replace grommet, they need an inside diameter of size 8 machine bolt and outside diameter of .485 - .495.
ETC Part Number Description
B109 SQUIRREL CAGE FAN 120 CFM