Cooling fan
Common VFD, drive, UPS, and cabinet overheating failure point.
Sullair Compressor Fault Codes - Quick Reference
Sullair rotary screw compressors use the Supervisor and Touch Panel controllers to display warning and shutdown alarms. Codes vary by model (S-Series, 900/1150 HH, ShopTek), but these are the most common alarm families.
| Fault | Meaning | Quick Fix |
|---|---|---|
| High Discharge Temperature | Outlet air/oil temp exceeds limit | Check coolers, oil level, ambient temp |
| Low Oil Pressure | Lubrication fault | Check oil level, filter, pump |
| High Oil Temperature | Oil overheating | Check oil cooler, oil quality |
| Motor Overload | Drive motor overcurrent | Check amps, voltage, load |
| E-Stop Active | Emergency stop tripped | Reset E-stop, inspect circuit |
| Service Required | PM interval reached | Perform scheduled service |
| Separator Differential High | Oil separator restricted | Replace separator element |
| High Sump Pressure | Sump pressure relief or blowdown fault | Check minimum pressure valve |
| Sensor Fault | Temp or pressure sensor out of range | Check wiring and sensor |
| Blowdown Fault | Blowdown valve not opening | Inspect blowdown valve |
Most Common Faults
High Discharge Temperature
The leading cause of Sullair shutdowns. Dirty oil cooler fins, low oil level, high ambient temperature, or a failed cooling fan all drive this fault. Start with cleaning the cooler with dry air blown against normal airflow. Check oil level when cool. Verify fan operation.
Separator Differential High
A restricted oil separator causes high pressure drop and oil carryover into the discharge air. Replace the separator element at or before the rated service interval. On Sullair units this is typically 2,000–4,000 hours depending on model.
Low Oil Pressure
Check the oil level first - if low, fill and reset. If oil level is correct, the oil filter may be bypassing or the scavenge line may be blocked. On older units, the oil pump pickup can become contaminated.
Motor Overload
Verify incoming voltage balance on all three phases. Unbalanced voltage causes disproportionate current draw on one phase and will trip the overload even at normal load. Also check the inlet valve if the compressor loads too heavily on startup.
Parts Often Needed
| Part | Notes |
|---|---|
| Air/oil separator element | Replace every 2,000–4,000 hours |
| Oil filter | Replace with separator service |
| Discharge temperature sensor | Common on high-hour units |
| Inlet valve kit | Common cause of motor overloads |
| Minimum pressure valve | Fails open causing high sump pressure |
Need Replacement Parts?
Before ordering, match the commercial equipment part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
Repeated discharge temperature trips after cleaning, or loss of oil pressure with correct oil level, indicate internal airend wear or oil pump failure. These require disassembly and should be handled by a Sullair-trained technician.