Symptom: | What it may indicate: | What you should do: |
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12.0Air dryer
safety valve releases air.
Air dryer safety valve
ð
êê
Technician removes governor.
13.0Reservoir
safety valve releases air
14.0Air dryer doesn’t purge. (Never hear exhaust from air dryer.)
15.0Compressor constantly cycles (compressor remains unloaded for a very short
(a)Restriction between air dryer and ð Inspect delivery lines to reservoir for
reservoir. |
| restrictions and repair as needed. | |
(b)Air dryer safety valve malfunction. | ð Verify relief pressure is at vehicle or | ||
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|
| component manufacturer specifications. |
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| Replace if defective. |
(c) Air | dryer | maintenance not | ð See Maintenance Schedule and Usage |
performed. |
| Guidelines (Table A, column 3, on page | |
|
|
| 18). |
(d)Air dryer malfunction. | ð Verify operation of air dryer. Follow vehicle | ||
|
|
| O.E. maintenance recommendations and |
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| component Service Data information. |
(e)Improper governor control line | ð Go to Test 5 on page 30. | ||
installation to the reservoir. |
| ||
(f) Governor malfunction. | ð Go to Test 4 on page 30. | ||
(a)Reservoir safety valve malfunction. | ð Verify relief pressure is at vehicle or | ||
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|
| component manufacturer's specifications |
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| (typically 150 psi). Replace if defective. |
(b)Governor malfunction. | ð Go to Test 4 on page 30. | ||
(c) Compressor unloader mechanism | ð Go to Test 6 on page 30. | ||
malfunction. |
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| |
(a)Air dryer malfunction. | ð Verify operation of air dryer. Follow vehicle | ||
|
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| O.E. maintenance recommendations. |
(b)Governor malfunction. | ð Go to Test 4 on page 30. | ||
(c) Air brake system leakage. | ð Go to Test 2 on page 29. | ||
(d)Improper governor control line | ð Go to Test 5 on page 30. | ||
installation to the reservoir. |
| ||
(a)Air | brake | charging system | ð Available reservoir capacity may be |
maintenance not performed. | reduced by build up of water etc. Drain | ||
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|
| and perform routine maintenance per |
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|
| Table A, columns 3 & 4, on page 18. |
time.)
(b)Compressor unloader mechanism malfunction.
(c)Air dryer purge valve or delivery check valve malfunction.
(d)Air brake system leakage.
ðGo to Test 6 on page 30.
ðVerify operation of air dryer. Follow vehicle O.E. maintenance recommendations and component Service Data information.
ðGo to Test 2 on page 29.
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