254
Air System
Air Dryer Troubleshooting
Possible Cause
Remedy
Problem #: Dryer is constantly cycling or purging.
Test for excessive leakage and repair.
B. Leakage in lines connecting compres-
sor, dryer, and wet tank
Test for leaks at fittings or valves and repair or
replace.
C. Defective check valve in dryer
Test check valve with soap solution. Leakage
should not exceed 1" bubble in 5 seconds. Re-
pair or replace valve if necessary.
D. Defective air governor
Test governor for proper cut-in and cut-out
pressures and leakage.
A. Excessive system leakage
E. Leaking purge valve in dryer
Remove end cover and apply 120 PSI at con
-
trol port. Allowable bubble is 1" in 5 seconds.
Repair or replace if necessary.
F. Compressor unloader leaking
With compressor unloaded, check for leakage.
Possible Cause
Remedy
Problem #2: Water in air tanks.
Replace desiccant cartridge.
B. Improper discharge line length or
material.
Minimum 6’ of metal line between compressor
discharge and dryer supply port.
C. Air system charges from outside source.
Outside air should pass through dryer. Practice
should be minimized.
D. Air dryer not purging
See Problem #5, later in this section.
A. Desiccant needs replacing
E. Purge time insufficient due to exces
-
sive leakage.
See Problem #1, earlier in this section.
F. Dryer application requires additional
purge volume
If compressor loaded more than 90 seconds in
normal use, extra volume may be needed. Call
Gillig Field Service before proceeding.
G. Improper dryer application
Dryer needs min. 30 sec. purge time. If load
time is 90+ sec., extra purge volume needed. If
load is 120+ sec., dryer efficiency decreases.
Summary of Contents for LOW FLOOR
Page 18: ...Specifications 18...
Page 58: ...Preventive Maintenance 58...
Page 110: ...Engine 110...
Page 138: ...Transmission Driveline Rear Axle 138...
Page 182: ...Suspension 182...
Page 260: ...Air System 260...
Page 420: ...Electrical System 420 Deutsch DT Series Connectors...
Page 421: ...Electrical System 421...
Page 422: ...Electrical System 422 Deutsch HD 10 Series Connectors...
Page 423: ...Electrical System 423...
Page 424: ...Electrical System 424 Deutsch HD 30 Series Connectors...
Page 425: ...Electrical System 425...
Page 442: ...Heating Air Conditioning 442...
Page 492: ...Body and Interior 492 Figure 11 33 USSC Seat Assembly...
Page 493: ...Body and Interior 493 Figure 11 34 USSC Seat Suspension Assembly...
Page 495: ...Body and Interior 495 Figure 11 37 Seat Air Connections...