Trane VAV boxes clicking

[b-man]

Have some older Trane VCEE VariTrane VAV boxes that intermitantly make a clicking noise. Is this actually the motor/gear wearing out, or the end switches not shutting off the motor, causing the motor to still try to drive, even when full open/closed?
They are in a tough position to get to, with only a small window of time to investigate, so I was hoping to get a head start on troubleshooting.
Thanks
b-man

[381engineer]

The brass bushings in the actuator motor may be worn out.
Take a large hole saw and cut yourself an access port and you can access the actuator motor without pulling out the airvalve.

[madhat]

First check your minimum CFM setting, ours somehow got set to 5%. They would sit there and search, making a Ehee, Ehee noise or a clicking noise. Trane Rep set the minimum at 20%. BTW we do not have access to system to set the CFM.

[basshound71]

Also if have electric heat in them it is probably the contactors pulling in and out. Make sure cfm is correct

[b-man]

Noise is definitely coming from motor/gear, not contactors. It is the old worm gear with the pie plate style air valve. Like I said bad location, equpment has to be moved and scheduled to troubleshoot. Noise is intermittant, so just trying to get some ideas to be able to get in/get out.
Thanks for the ideas
b-man

[madhat]

I've had good luck quieting MetalAire Controllers, clock motors by applying Dielectric grease to the Brass bearing and shaft while the motor is running. Place a little on your finger and work it into the bearing. Just don't touch your eyes till you've washed your hands.

[381engineer]

Noise is definitely coming from motor/gear, not contactors. It is the old worm gear with the pie plate style air valve. Like I said bad location, equpment has to be moved and scheduled to troubleshoot. Noise is intermittant, so just trying to get some ideas to be able to get in/get out.
Thanks for the ideas
b-man

I've got a bunch of Trane C boxes in my building. It is most likely the actuator motor bushings are worn and the slop allows the gears to skip when it reaches the end of travel right before the micro switches shut it off.
I too have been able to quite some by greasing the shaft with a light coating of bearing grease but if the motor shaft has too much slop you will have to replace.

I have had good success cutting a hole in the side with a 6" hole saw which gives you just enough room to pull the whole motor/microswitch assembly out.
Otherwise you need to pull the whole airvalve out the front.

Lots of fun, good luck.