Trane RTAA variable speed (inverter) fan module troubleshooting

[MrSlim]

I've had to replace several of the variable speed (inverter) fan modules on our Trane RTAA Chillers. Is there any information on troubleshooting boards? What are the causes of board failures? Does anyone know the sequence of operation or what signals are sent to the boards from where?

JCI P/N VFD66HCB TRANE P/N X1317 0220 070

[Doesn'tPhaseMe]

http://hvac-talk.com/vbb/showthread.php?t=474632&page=2

There is a post in it that has an RTAA troubleshooting manual with an inverter section.

[danno062]

I have found these inverters to be bad as well. all i was told to do was to either get rid of it or put a pressure switch in to operate it. they just dont seem to last. im curious to know what others have found on this

[acjourneyman]

I think these are influenced by incoming line conditions heavily. I have chillers that are over 10 years old where they are original and have one chiller where I replaced 3-4 of them and finally had to bypass them alltogether. I never could find a reason for them failing and couldn't justify the cost to the customer to keep changing them.

[scott_RWS48]

Do not replace the inverters with pressure switches. The inverters are a critical part of controlling differential pressure especially at start up. They do fail but considering the environment they are in it should be expected.

[MrSlim]

http://hvac-talk.com/vbb/showthread.php?t=474632&page=2

There is a post in it that has an RTAA troubleshooting manual with an inverter section.

Thanks for the Troubleshooting Manual! I've been trying to keep (9) RTAA Chillers running for the past 5 years with an IOM. No wonder I have gray hair...... Thanks again!

[R123]

You would never want to replace the inverters with pressure switches. If you want to bypass the inverter, you need to go into the configuration settings and disable the inverter for that circuit. That will change the fan staging algorithm to operate as if the chiller didn't have an inverter. If you do bypass the invertes, you need to install half airflow fan blades on the motors that had the inverters. Then go into the configuration settings and select half airflow fan to again change the fan staging algorithm. This setting will stage the half airflow fan as a half step between adding the next fan. The half airflow blade will allow the chiller to run in colder ambient temp.