Graco 3A0420T Manual De Usuario
Troubleshooting
3A0420T
33
Troubleshooting
✖ Fluid ratio will be wrong.
◆ Purge all air from system before proportioning
◆ Purge all air from system before proportioning
fluids.
Problem
Cause
Solution
System stops or will not start.
Air pressure or volume too low.
Increase; check air compressor.
Closed or restricted air line or air
valve.
valve.
Open or clean.
Fluid valves closed.
Open.
Clogged fluid hose.
Replace.
Air motor worn or damaged.
Repair air motor; see 311238.
Displacement pump stuck.
Repair pump; see 311762.
System speeds up or runs erratically. Fluid containers are empty.
◆
Check often; keep filled.
Air in fluid lines.
◆
Purge; check connections.
Displacement pump parts worn or
damaged.
damaged.
Repair pump; see 311762.
Pump operates, but resin output
pressure drops on upstroke.
pressure drops on upstroke.
✖
Dirty, worn, or damaged resin pump
piston valve or piston packings.
piston valve or piston packings.
Clean, repair pump; see 311762.
Pump operates, but resin output
pressure drops on downstroke.
pressure drops on downstroke.
Dirty, worn, or damaged resin pump
intake valve.
intake valve.
Clean, repair pump; see 311762.
Pump operates, but resin output
pressure drops on both strokes.
pressure drops on both strokes.
✖
Hardener output restriction.
Clean, unplug hardener side. Open
manifold restrictor.
manifold restrictor.
Fluid supply low.
◆
Refill or change container.
Pump operates, but hardener output
pressure drops on upstroke.
pressure drops on upstroke.
✖
Dirty, worn, or damaged hardener
pump piston valve or piston pack-
ings.
pump piston valve or piston pack-
ings.
Clean, repair pump; see 311762.
Pump operates, but hardener output
pressure drops on downstroke.
pressure drops on downstroke.
✖
Dirty, worn, or damaged hardener
pump intake valve.
pump intake valve.
Clean, repair pump; see 311762.
Pump operates, but hardener output
pressure drops on both strokes.
pressure drops on both strokes.
Resin output restriction.
Clean, unplug resin side.
Fluid supply low.
◆
Refill or change container.
Fluid leak in packing nut.
Loose packing nut or worn throat
packings.
packings.
Tighten; replace; see 311762.
Fluid leak under packing nut
Packing cartridge o-ring.
Replace o-ring; see 311762
Relief valve (AM) leaks back to sup-
ply, opens too soon, or will not close.
ply, opens too soon, or will not close.
Relief valve is dirty or damaged.
Replace over pressure relief
valve (302)
valve (302)
No pressure on hardener side; fluid
leaking from hardener pump outlet
rupture disc fitting.
leaking from hardener pump outlet
rupture disc fitting.
Overpressure rupture disk blown.
Determine cause of overpressuriza-
tion and correct. Replace rupture disk
assembly 258962 (see page 51) and
over pressure relief valve (302).
tion and correct. Replace rupture disk
assembly 258962 (see page 51) and
over pressure relief valve (302).
Pressure and flow surges on
upstroke.
upstroke.
Feed pressure too high. Every 1 psi
of feed pressure adds 2 psi during
upstroke.
of feed pressure adds 2 psi during
upstroke.
Reduce feed pressure. See