HVACknowledge

Easily wire the Trane Precedent Power Exhaust.

Testing a 4-20 mA building space pressure transducer connected to Trane BAS. 1) Measure actual building space pressure at the transducer tubing. If it’s measuring reasonably well based upon your observation, continue troubleshooting. If you have reason to believe the tubing is sampling from a poor location, relocate the sampling tubes’ termination point after verifying the tubing isn’t damaged or plugged. 2) In this case, my dual port manometer verified the building is under a reasonable slight positive pressure of 0.05” wc. I reconnected the transducer tubing and disconnected one of the two transducer signal wires and measured its mA output with my meter in SERIES. It read 0.01 mA or effectively zero. 3) I tested the BAS ability to translate the signal with a signal generator. At 12 mA it read effectively 0.0” wc or a neutral building pressure accurately. 4) My last step is to verify the control wiring integrity. I’ll check for shorts or breaks in the wiring. 5) If the wiring is damaged, we’ll replace the wiring and retest the signal. If the wiring is good, we’ll replace the transducer.

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.)

YOU are responsible for receiving proper SAFETY and DIAGNOSTIC and REPAIR training! KNOW PROPER Lock Out Tag Out procedures! WEAR proper PPE! Please work safely and do not rush. This video is meant for HVAC technicians that are properly licensed and insured or work for licensed and insured companies! Watching this video does not in itself qualify you to work on this equipment. It is only meant to be a guide for those in the industry that are also following safe working procedures! 1) Verify proper airflow across the condenser. Check ALL condenser fan motors, fan blades, and wiring. Check for dirty condenser coils. Verify proper condenser temperature thermistor readings. 2) Check for tripped compressor circuit breakers. If they’re tripped, check for a short to ground and a short across windings. If no short is detected with your multimeter, use a megger. (WARNING: Get proper training on how to use a megger to avoid INJURY or equipment DAMAGE!) If no short is detected, check for LRA. If the compressors check out, verify that the compressor circuit breaker is operating properly. If the compressor circuit breaker is NOT tripped, ensure the compressor circuit breaker auxiliary is operating properly. (N.O. means the Aux is open when the breaker is off or tripped.) 3) Check the 1F44 and 1F45 fuses, their contact in the socket, and their wiring. 4) Check the compressor module (in the compressor mounted junction box) for proper operation. Verify the compressor module thermistor is working properly. If desired, buy the adapter tool from Trane Parts and connect with your Android phone. Download the INTspector app to your Android device. 5) If you cannot pinpoint the cause of the diagnostic, install a *** fast acting 50 mA 250 VAC indicating fuse *** in PARALLEL with the safeties in this specific circuit. (See the Compressor Module wiring schematic. HPS, Compressor Module M1-M2, and Compressor Circuit Breaker Aux Switch.) If a safety opens even briefly, the 50 mA fuse cannot handle the load of the circuit and will open. When you return, locate the blown fuse and that’s the safety that’s opening. Verify if the safety is working properly or if the safety is faulty and remedy the problem. DO NOT use a higher rated fuse as this may bypass a safety possibly resulting in equipment damage!