ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 012-016   Air Governor

The air compressor governor location can vary. The air governor can be air compressor mounted or chassis mounted.

If the air pressure is being governed at either a higher or lower pressure than the equipment manufacturer’s specification, connect a regulated shop air pressure line to the air compressor governor air signal port.

NOTE: Be positive the gauge is accurate and the supply lines and fittings are in good condition before performing any air pressure checks. Use a master gauge of known accuracy to check the air pressure gauge.

NOTE: When performing the test, be sure the air system pressure does not exceed the manufacturer’s maximum allowable pressure.

NOTE: Make sure the governor vent port (A) is open to the atmosphere. If this port is plugged, the air governor will malfunction.

• Inspect the governor control lines for restrictions.
• Drain the air system and install a gauge of known accuracy onto the unloader port (B) of the air governor. If the governor has two unloader ports, make sure one is plugged.

• Start the engine and apply the brakes to initiate air compressor pumping. Note the governor cut-out pressure (pressure at which the compressor stops pumping).
• Apply the brakes until the compressor starts to pump. Note the cut-in pressure.
  

  NOTE: Zero pressure in the governor unloader line will allow the compressor to start pumping.

• Allow the system to build pressure until the air compressor unloads.
• Apply the brakes until the compressor starts to pump. Note the time it takes for the governor unloader port to go from system pressure to 0 kPa [0 psi]. The cycle should take less than 2 seconds.
• Repeat steps three through six for a total of three runs.