Oil System Fault

Issue:

Oil System Fault

Resolution:

RTAA 70-125, RTUA 70-125, RTWA 70-125 TON Chillers:

Description of Fault: Entering oil temperature on either compressor of the given circuit reads a temperature of 4 F below the given ckt sataurated condenser temperature for more than 30 mins. Where 4F is the oil loss differential. (2 F hysteresis to clear timer).

Oil System Fault can be caused by numerous issues; items to test, check, and verify:

• Condenser Temperature Sensor accuracy.  Check via RLC-SVD03A-EN p15-18.
• Oil Temperature Sensor accuracy.  Check via RLC-SVD03A-EN p15-18.
• Saturated Evaporator Temperature Sensor and Compressor Suction Temperature Sensor accuracy.  Check via RLC-SVD03A-EN p15-18.
  • Inaccurate sensors can causes EXV to go wide open and flood evaporator and then carry over to the oil separator causing a false reading on the oil temperature sensor.
• EXV Control/Operation:
  • EXV could be stuck open flooding the evaporator and causing carry over. The liquid refrigerant will flash once it gets to the oil separator and cause the oil temperature to drop. Do a stroke test and check for refrigerant flow. Do a complete check of EXV via RLC-SVD03A-EN pages 58-71.
• Oil Filter plugged.  New filter pressure drop should be approximately 5 psid.  Refer to RTAA-SVX01A-EN p121-124.
• Kepner Valve (Oil Check Valve internal to compressor, located in the Oil Filter Cover Plate)
• Orifice Issues
  • If new compressor, one or more incorrect orifice(s)
  • If service compressor, one or more incorrect orifice(s)
  • Contact Technical Support for information
• Failed Gaskets between the Bearing Housing Cover-plate and Bearing Housing
  • Measured pressure drop from the Oil Filter Cover-plate and the Bearing Housing is too good...below the published curve in the IOM. See Oil Pressure Drop curves in IOM.
  • Noisy Compressor
  • See attached drawing for internal gasketing and spacer/plate. (click here)
  • Replace the Spacer/Plate
  • Install new internal gaskets
• Check compressor starting RLA. If it is above minimum you could have male load solenoid leaking by or female step loader staying energized or stuck closed. Check schrader ports for female step pressure behind piston and Male slide valve. At start up pressure on female should be at suction pressure for the first 1.5 to 2 minutes and male piston pressure should be at suction.
• Oil overcharge will cause the oil separator to be inefficient, and oil will carry over to evaporator, causing foaming and refrigerant carry over to oil separators. This causes refrigerant to flash in the oil separator and lower the oil temperature. Sometimes the oil separators will vibrate due to the refrigerant boiling off. The oil separators will feel cooler than normal.

Notes:

Field Testing Example:

Pressures:
Suction: 85 psi
Discharge: 160 psi
Comp Oil supply: 116 psi
Oil Filter Cover: 116 psi

Temperatures:
Sat Evaporator: 46.9F
Sat Condenser: 84.3F
Entering Oil: 79.5F
Suction: 50.9F
Ambient: 54.7F
Compressor:
RLA: 42%

Conclusion: the differential pressure (suction to discharge) = 75 psi and across the compressor (Oil Filter Cover-plate to Bearing Housing) is 0 psi. This is not on the operating map of the compressor and shows an internal leak on the compressor at the spacer plate between the discharge plate and the bearing housing.

Changes:

Other Question/Problem/Cause Statements:

• Oil System Fault?
• CHHN (GP) Compressor?
• Noisy Compressor?
• Noisy CHHN Compressor?
• Noisy GP Compressor?
• GP Compressor Noise?
• GP1 Compressor Noise?
• Noisy GP1 Compressor?
• Oil Line Vibration?
• Oil Line Failure?
• Compressor Vibration
• Compressor Oil Line Vibration?

Facts:

• CHHN Compressor
• GP1 Compressor
• Air-Cooled Chiller (Pueblo) (RTAA 70-125 Ton)
• Compressor Chiller (Pueblo) (RTUA)
• Water-Cooled Chiller (Pueblo) (RTWA)

Original HUB Document : DOC-106067

WARNING:

Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.