Applicable Systems
Octagon 4-Comp
Symptoms
Capacity controller displays A2, indicating an oil differential pressure fault. The oil pressure has dropped below the minimum threshold of 5 bar (72 psi) differential for more than 30 seconds during compressor operation.
Possible Causes
- Low compressor oil level - check oil sight glass
- Clogged oil filter restricting oil flow to bearings
- Worn oil pump reducing oil delivery volume
- Excessive bearing clearance causing internal oil pressure loss
Troubleshooting Steps
- Step 1: Check the compressor oil sight glass - oil level should be visible at 1/3 to 1/2 of the sight glass
Add approved oil if level is low, monitoring while compressor is running - Step 2: Check oil filter differential pressure if equipped with a serviceable filter
Replace filter if pressure drop exceeds 1 bar (14.5 psi) - Step 3: Verify oil pump operation by checking oil pressure at the pump outlet port
Compare with manufacturer specification for the specific compressor model - Step 4: If oil pressure remains low after filter service, inspect bearing clearances
This requires a qualified technician to perform internal inspection
How to Reset
To reset A2: 1) Ensure oil level is adequate. 2) Acknowledge the alarm on the capacity controller. 3) Press the reset button. 4) The compressor restarts after the anti-short-cycle delay.
Common Replacement Parts
- 610-000-003: Bitzer Octagon oil filter element (Replace at intervals per service schedule)
- 610-000-004: Oil pressure differential switch, 5 bar threshold (Verify setpoint matches compressor specification)
Frequently Asked Questions
- Q: What is the correct oil level for a Bitzer compressor?
The oil level in the sight glass should be visible at approximately 1/3 to 1/2 of the glass when the compressor is running. When stopped, the level may rise slightly.
- Q: How often should the oil filter be changed?
Replace the oil filter at the first 500 running hours, then every 10,000 hours or annually, whichever comes first. More frequent replacement may be needed in harsh operating conditions.
Source: Bitzer Octagon Compressor Service Manual, Edition 2018
Category: Refrigeration