JLG 740AJ Service Manual - Manual (Page 214)

SECTION 3 - CHASSIS & TURNTABLE
3-162 – JLG Lift – 3121160
Table 3-16. Air Compressor Troubleshooting
SYMPTOM PROBABLE CAUSE SOLUTION
1. Compressor shuts down with air
demand a. Compressor temperature; switch
opening.
b. Plugged oil filter
c. Dirty cooler core
d. Contaminated cooler core
e. Hydraulic pressure & Flow incorrect
a. Low oil level-top up. Restricted cool-
ing air intake- clean-reposition machine.
Fan not operating-check ground-check
fan switch.
b. Replace
c. Clean
d. Remove and clean
e. Adjust and reset
2. Compressor will not build up pressure a. Air demand too great
b. Air filter plugged
c. Press. switch out of adjustment
d. Defective pressure switch
e. Motor does not speed up
f. Belts slipping
g. Service valve wide open
h. Sol. valve stuck
i. Leak in air pilot line
a. Check for leaks and correct Too much
air demand
b. Check and replace
c. Reset
d. Replace
e. Pressure switch Check hydraulic flow
& pressure
f. Readjust/tighten
g. Close
h. Replace
i. Check for leaks & correct
3. Compressor over pressures a. Press. Regul. out of adjustment
b. Defective press. switch
c. Leak in air control line
d. Inlet valve stuck
e. Restriction in control line
f. Sol. valve not energized/faulty
g. Faulty gauge
h. Defective safety valve
i. Plugged coalescer
a. Reset
b. Replace
c. Check and correct
d. Free or replace
e. Dirt or ice, clean/free up
f. Check for power/replace
g. Check with shop air/replace
h. Replace
i. Replace