JLG 740AJ Service Manual - Manual (Page 215)

SECTION 3 - CHASSIS & TURNTABLE
3121160 – JLG Lift – 3-163
4. Insuf6cient air delivery a. Plugged air filter
b. Plugged coalescer
c. Motor speed too low
d. Inlet valve stuck
f. Belts slipping
a. Replace
b. Replace
c. Check hydraulic flow & pressure
d. Free or replace
f. Readjust
5. Oil carryover a. Oil level overfull
b. Plugged oil scavenge line
c. Discharge pressure too low
d. Defective coalescer
a. Drain to correct level
b. Remove and clean
c. Check minimum pressure valve
d. Replace
6. Compressor overheating a. Insufficient oil
b. Restricted cooling air flow
c. Fan not operating
d. Plugged oil filter
e. Cooler core plugged
f. Pressure set too high
g. Contaminated cooler core
h. Running too fast
i. Thermal Valve – element faulty
a. Check level and top up
b. Reposition machine
c. Check ground connection; Check fan
switch; Check air pressure switch; Check
circuit breaker; Check for shorted wires;
Check fan motor
d. Replace
e. Clean
f. Readjust
g. Remove and clean
h. Check hydraulic flow & pressure
i. Replace
Table 3-16. Air Compressor Troubleshooting
SYMPTOM PROBABLE CAUSE SOLUTION