Trane RTAA Air Cooled Screw Chiller EXV Troubleshooting

Trane RTAA Air Cooled Screw Chiller EXV Troubleshooting

***DANGER*** All Troubleshooting and repairs must be performed by qualified, licensed technicians/contractors according to your local jurisdiction. Proper lock out tag out procedures must be followed to protect yourself from injury or death.*** Always verify the specifications of the equipment you’re working on with the IOM or manufacturer.

Never remove pin plugs during operation. Try to perform all tests with unit powered off where possible. When removing or installing a circuit board, I recommend using a grounding strap to ground yourself to the chassis of the equipment. Failure to do these things may result in static damage to the board necessitating replacement of the board. This rule applies to all the modules within the cabinet.

“EXV Elec Drive Ckt - Rfgt Ckt 2” fault found on this Trane screw chiller. I walk through some simple troubleshooting tips to identify the root cause. Please bear with me as I do not have a GoPro type camera. I’m shooting this live with a phone. Just want to get some tips out to you HVAC folks.

When performing the EXV test function through the Adaptive Control (Clear Language Interface - CLI) the stepper motor on the EXV should cycle closed and open for about 25 seconds in total.

“J4” Ckt 1 EXV control
“J5” Ckt 2 EXV control

“J4” & “J5” pins to EXV Module edge ground (on edge of circuit board) should be 100k - 350k ohms to ground. (Ensure your meter is capable of reading sufficient resistance.)