VMAC - Vehicle Mounted Air Compressors
VMAC Technical Support: 888-241-2289
VMAC Knowledge Base: www.kb.vmacair.com
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Performance Testing and System
Adjustments
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Install the VMAC test tool at the AOST outlet with the 150 cfm (0.250 in) orifice.
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Ensure the ball valve is closed.
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Place the transmission in “PARK” and fully apply the park brake.
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Allow the engine to run until it is at operating temperature.
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Turn on the air compressor system and allow it to operate until the oil is warm.
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Observe the pressure gauge. Pressure should be approximately 150 psi.
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Open the ball valve on the test tool and observe the engine tachometer. Engine
speed should increase to approximately 2,000 rpm - 2,500 rpm. The pressure
on the gauge should be 90 - 120 psi.
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Close the air valve slowly to allow the system pressure to rise. When the
pressure reaches 150 psi (factory setting), the system will close the inlet valve
poppet and reduce the engine speed to VMAC base idle.
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Once the system pressure is at maximum, slowly open the ball valve on the
test tool until the pressure on the gauge begins to drop. Engine speed should
ramp up when the pressure drops to approximately 140 psi. This value can be
adjusted via the “IDLE DOWN PRESSURE” adjustment.
Performance Testing and System Adjustment
System operation can be tested using the tools that will be operated by the
system or by using the VMAC Test Tool (A700052) with the 150 cfm (0.250 in)
orifice in the outlet to simulate tool use (Figure 129).
Disconnect all downstream equipment (hose reels, etc.) and connect
the test tool directly to the discharge fitting on the AOST.
Ensure there are no leaks in the test tool. The system may not idle
down if there are leaks in the lines or fittings.
Figure 129 — A700052 VMAC Air Test Tool
Install orifice here
Orifice
Ball valve
JIC Adapters
