Bendix Commercial Vehicle Systems AD-SP SYSTEM PURGE AIR DRYER 10/04 - Manual (Page 29)

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Complaint: System Pressure Goes to 150+ psi
• Drain the air system to zero (0) psi, remove/disconnect
the governor from the compressor. Start the engine
and note the air pressure rise on the dash gauges.
Apply 120 psi of shop air to compressor unloader port.
If the air pressure continues to rise, repair compressor
unloaders or replace compressor. If air ceases to rise,
repair or replace governor.
COMPLAINTS COMMON TO THE CHARGING & AIR SUPPLY SYSTEM
Complaint: Low Pressure Warning After Only 1
or 2 Applications
• Brakes out of adjustment: adjust brakes.
• Excessive system leakage on the service (application)
side of system: Build the system pressure to 120 psi
and turn the engine off. With the park brakes released,
make a full service application and note the dash
gauges for two (2) minutes. A pressure drop on either
gauge should not exceed 4 psi. (two (2) psi per min.)
If the pressure drop is excessive, find the leakage in
service system, if OK, then proceed to next complaint.
• Incorrect low pressure switch in use or setting
incorrect: Build the system pressure to 120 psi, with
the engine OFF and the ignition ON, slowly drain the
air pressure from one service reservoir. Low pressure
warning on at minimum 60 psi, maximum 10–15 psi
less than governor cut-in pressure.