Trane Model CVHG 480 Leak Unfound

[rickyccong]

"Trane" Model CVHG 480 Motor and Compressor send for repairs due to leakage of tubes. Condenser and Evaporator Eddy Current Tested and retubed nine (9) tubes with about 80% -90% wall loss. Pressure tested to 5 PSI and hold pressure for 16 hours without pressure drop.

Vacuum out the moisture but unable to carry out full load, suspected tubes leakage.

All tubes end at tubesheet lightly plugged with rubber taper plugs, expanded all tubes expansion end and reapply pressure with N2 on Condenser side to 8 PSI, scanned all tubes on Condenser and Evaporator with SPM Model L10 Ultrasonic Leak Detector, pressure dropped by 1.2 PSI and maintained at 6.8 PSI. after forty two (42) hours dropped only 1.2 PSI. All the rubber plugs and no rubber plugs drop out, presume tubes not leaking.

Need kindest HELP from all members whoever come across such problems for guidance and advice on such problem.

[serviceman]

leak check the entire drive, remove the ruptured disk and place a blank flange, increases the pressure to 20 psig, the motor terminals sometimes leaks as well as the flanges of the economizer.

good luck

[rickyccong]

Thanks Serviceman, the carbon rupture disc blow-out and blank off with a blind steel flange.
Also forgotten to give the information, when the contractor installed back the compressor and motor, pressure tested to 15 PSI without sign of leak after holding for more than 24 hours.
When the contractor start vacuum with new vacuum pump that's where the problem start, could the negative pressure apply too great that created the leak?.
Since I failed this mission of detecting the leak, I hand back to the contractor but still feel not happy about failed mission that's where I turn to RE for professional advice to solve the problem.

[allchlrstech]

Is the purge valves open,if they are try Isolating the purge and pull another vacumme.The purge solinoids will sometimes leak under a vacumme.
They also have to be installed correctly.

[rickyccong]

Thanks Allchlrstech, it's not as well. Maybe I am in the wrong thread for water cool chiller.? If Yes, please guide me to the right thread?
Thanks

[serviceman]

question.

water entered the condenser or evaporator? humidity and that you may vary the negative pressure