Graco Inc. UNICARB Pro AA4500 - Manual (Page 23)

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Gun Operation Troubleshooting
PROBLEM CAUSE SOLUTION
Leakage from fluid needle area Fluid needle packings loose
Fluid needle packing damaged
Tighten packing nut; See page 33
Replace fluid needle; See page 34
Air leakage from front of gun Air valve not turned off
Piston air valve not seating properly
Turn off air (43). See page 15
Clean, Service; See page 39
Fluid leakage from front of gun Fluid needle worn
Fluid seat loose or worn
Spray tip loose
Tip seal damaged
Replace fluid needle; See page 34
Tighten or replace fluid seat
Tighten retaining nut
Replace tip seal; See page 29
“Orange Peel” finish CO 2 percentage is too low
Fluid pressure too low
Spray tip or pre-orifice too large
Fluid poorly mixed or filtered
Improper thinner being used
Increase CO 2 percentage
Increase fluid pressure with gun fluid regulator*
Use a smaller size spray tip or pre-orifice;
See page 47
Remix or refilter fluid
Use proper thinner
Excessive spray fog Fluid thinned too much Properly thin fluid
No fluid sprays from gun Fluid supply low
Spray tip or pre-orifice is dirty or clogged
Spray tip damaged
Fluid needle damaged
Check; Add fluid if necessary
Clean spray tip and pre-orifice; See page 20
Check; Replace spray tip; See page 29
Replace fluid needle; See page 34
Equipment covered with fluid Booth exhaust air flow too low or not
directed properly
Improper distance between gun and
workpiece
Check for proper CFM; Check baffles and
direction of air flow
Adjust spraying distance to 8 to 12 inches
(203 to 305 mm)
Paint build-up on air cap CO 2 percentage too high
Air cap dirty
Reduce CO 2 percentage
Clean air cap; See page 20
Fluid doesn’t shut off properly Seat housing over-tightened
Fluid leakage buildup on fluid needle
Fluid packings too tight
Replace seat housing; See page 29
Replace fluid needle; See page 34
Adjust fluid packings; See page 34
* Use the least fluid pressure needed for good results.