VMAC - Vehicle Mounted Air Compressors
VMAC Technical Support: 888-241-2289
VMAC Knowledge Base: kb.vmacair.com
79
Compressor Connections
Start the engine, and monitor both pressure gauges:
1. As the pressure indicated on the VMAC test tool gauge reaches 140 psi,
the gauge connected to the 1/4 in PTFE tube should indicate 140 psi. If the
pressure on the gauge connected to the 1/4 in PTFE tube does not increase,
confirm the manual unloader valve has not been adjusted. If the unloader
valve has not been adjusted the discharge valve needs to be replaced.
2. As the pressure indicated on the PTFE Test Tool gauge connected to the 1/4 in
PTFE tube reaches 140 psi, the throttle actuator rod should move to the right
and the engine rpm should decrease. If the throttle actuator rod does not
move, diagnose or replace the throttle actuator.
3. When the system pressure indicated on the VMAC test tool reaches 140 psi,
the pressure indicated on the gauge connected to the 1/4 in PTFE should
hold steady at 140 psi. If the pressure does not hold, check for air leaks or a
defective throttle actuator.
4. Slowly open the test tool ball valve. The pressure on both gauges should drop
at approximately the same rate until pressure at the discharge valve reaches
120 psi. Once the discharge valve pressure drops to 120 psi, the discharge
valve will close and the PTFE test tool gauge will indicate 0 psi. If the
pressures do not drop at the same rate, the discharge valve may be plugged.
Figure 53 — Compressor connections
Throttle (3/16 in
pressure control tube)
Throttle (1/4 in
pressure control tube)
Air bleed muffler
Scavenge
Oil return
Discharge
