RTAA Transition fault

[madhat]

I got the call at 0600 this morning on the chiller, said it was a Transition fault, chiller was running. They looked at the code and returned to operating window of 74. Said it was no longer flashing. Told me to wait till Monday, not to run the call. Of course I couldn't go back to sleep. I don't have my manual at home on the unit. They didn't toggle the unit off, is it truly reset? What is this fault?

[txhvac]

A transition fault is on wye-delta starters, means that the module is not receiving signal that you had a complete transition to start the compressor. Things you can look at, check your starters- make sure they're not burned up or full of carbon, check all wire connections, check aux. contacts make sure they are pulling in & out accordingly, make sure you have correct line voltage. Hope this helps, post back on what you find.

[maxster]

the IOM on that unit has it as a manual reset required to restart that circuit...# 180 is the code given for transition fault the UCM must see TR between 1 to 6 seconds or faults out.could of been power in or a pin loose to the UCMs ....repin and hit all your terminals with a screwdriver and check those AUXs on the contactors

[amjoecool]

First, is this a repetitive problem or just a nuisance trip? I wouldn't worry too much if it happened once and didn't repeat. These units have stacked auxillary contacts on the compressor contactors. The transition contact is on the "top" of the stack or the last contact to see the main contactor action. Often you can move the last set of auxillarys to the bottom of the stack and see if that works. If not, replace the auxillary contacts.

[madhat]

Thanks for the help, I was worried it was reset and running wounded. Never saw that fault before, we had a lot of wind Friday and Saturday, so the power was probably flickering. Gives me an excuse to shut down the Chiller Monday morning, do a turn down and inspect all the contactors. Got put on this Chiller in July to repair 80% start on Compressor "B" Have kept weekly and monthly logs since then. I've done some work in the past on these chillers, but as you know Trane is Stingy with any info.

[Randy S.]

My best guess is the plugs onto the board were loose on the pins. Also suspect was the aux contact for transistion made.

Anyhow, it quit doing it.

[madhat]

I did a turn down on all the wiring in the unit. Found loose connection on "A" Compr. auxillary contacts. The terminals behind the center support for the doors were loose,like they were never tightened. The Chiller wasn't called for all week and I couldn't get them to put it in override for an hour, so I'll have to keep an eye on it.