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Oil safety control trips

What is going on

Possible causes and checks for: oil safety control trips.

Likely causes

  • Low net oil pressure (pump pressure − crankcase pressure) for longer than the delay: oil loss to system (no separator/bad float)
  • Oil binding in evaporator
  • Poor oil return (suction drier pressure drop
  • Undersized lines)
  • Worn oil pump
  • Liquid in crankcase

Check in this order

  1. Net oil pressure, oil level, separator float, return line solenoid/thermostat, suction drier ΔP, level regulators on racks

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Source: General HVAC service practice — verify per model. Written in our own words; check the manual for your exact model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.