Applicable Systems
Carrier Transicold Refrigeration Unit
Symptoms
The Carrier Transicold unit displays alarm CR004, indicating low oil pressure differential. The oil pump discharge pressure is not sufficiently higher than the crankcase pressure, risking inadequate lubrication.
Possible Causes
- Oil level in the crankcase is below the minimum, starving the oil pump
- Oil filter is partially blocked, restricting flow from the pump to the bearings
- Oil pump internal relief valve is stuck open, bypassing oil back to the crankcase
Troubleshooting Steps
- Step 1: Check the oil level sight glass on the compressor crankcase
Oil level is at or above the center of the sight glass, confirming adequate oil supply - Step 2: Inspect the oil filter differential pressure indicator
Indicator shows green or the differential is below 0.5 bar, confirming the filter is not blocked - Step 3: Measure the oil pump discharge pressure and compare it to crankcase pressure
Differential is at least 1.5 bar, confirming the oil pump is delivering adequate pressure to the bearings
How to Reset
To reset: 1) Add oil to the correct level. 2) Replace the oil filter if blocked. 3) Replace or repair the oil pump. 4) Press RESET and monitor oil pressure for 30 minutes of operation.
Source: Carrier Transicold Refrigeration Unit Manual, Carrier Corporation
Category: Refrigeration