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978-368-3325
Compactors · Electrical · E-11

Your “Container Full” Light Is On and the Container Isn't

A full signal on an empty container means the circuit that detects fullness is reporting something that is not happening. Pressure switch set too low or failed closed, a latch relay stuck in, a PLC counter never cleared after the last pull, or a failed reset button. Of every fault on this site, this is the one most likely to be quietly costing you money on the hauling invoice.
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Serving Massachusetts, Connecticut, Rhode Island, New Hampshire, Vermont and Maine from Clinton, MA.
6 Symptoms

This Fault Has an Invoice Attached

Most faults cost you a repair. This one costs you a repair and a hauling bill, every month, quietly.

Count the pulls since the light started misbehaving.

Off the hauling invoices, same as any other month.

Ask what the containers looked like.

A driver or a dock supervisor usually remembers pulling containers that were obviously not full.

Multiply the extra pulls by your per-pull charge.

Haul fee plus any disposal that scales with the pull.

That is the running cost of a pressure switch.

Which is usually a small fraction of one month of it.

The version nobody notices

A full signal that is only slightly early does not look like a fault at all. The container gets pulled at eighty percent instead of full, month after month, and nothing on site looks wrong. It shows up as a hauling bill that crept up and never came back down.
Step One

The Reset Test

Two minutes, no tools, and it separates the cheap cause from the expensive ones.

Empty or confirm the container is not full.

The test only means something with a container that genuinely has room.

Perform a proper reset.

However that machine's reset is meant to be done — the button, the key, the sequence. Ask whoever normally does it.

Watch whether the light clears.

If it will not clear at all, the fault is in the latch or the reset circuit.

If it clears, run one cycle and watch again.

A light that clears and then comes straight back on the first cycle points hard at the pressure switch.

Note which of those two happened.

That one observation is most of the diagnosis and it costs you nothing.

Narrowing It

Four Causes, Cheapest First

  • Pressure switch set too low — The switch is calling full at a pressure the machine reaches long before the container is packed. Test and reset to spec, or replace.
  • Pressure switch failed closed — The switch is reporting full continuously regardless of pressure. Replacement, and it is an inexpensive part.
  • Latch relay stuck in — The relay that holds the full signal has welded or stuck contacts and will not drop out on reset. Common on older relay-logic panels.
  • PLC counter or logic not clearing — On a controlled unit, a cycle counter or a stored fault that is not being cleared by the reset. Diagnosis and sometimes a logic correction.
Why It Matters

It Does Not Fix Itself and It Hides the Opposite Fault

The cost accrues monthly

Every pull of a container that was not full is money spent, and unlike most faults there is no operational pain to prompt anyone to act.

It trains people to ignore the light

Once a site learns the full light lies, nobody believes it — including when it is finally telling the truth. Overfilled containers, jammed doors and warped doors follow.

The fix is usually small

A pressure switch is one of the least expensive components on the machine. This is a fault where the diagnosis costs more than the part, and the delay costs more than both.
Before You Call

What We Need to Quote It

You do not need all of this — the make and model plus photos is usually enough to get started. But the more of it you have, the closer the first number is to the final one.
  • Bore — Inside diameter of the barrel. Stamped on many data plates; otherwise we measure it.
  • Stroke — Fully extended length minus fully retracted length.
  • Rod diameter — Across the chrome, measured with calipers if you have them.
  • Mount type — Clevis, cross-tube, trunnion or flange — and the pin diameter.
  • Pin-to-pin retracted — Center of one mounting pin to center of the other, ram fully in.
  • Ports — Size, thread type, and whether they face the same direction or opposite.
  • Machine make and model — Off the data plate. It often tells us the cylinder before you measure anything.
  • Photos — The whole cylinder in place, both mounting ends, and a close shot of the rod.

If you can't get the measurements

Don’t climb on the machine to get them. Send the make, the model and the photos, and we will take the dimensions when the cylinder is out — or bring a replacement with us if we already know that machine.
Safety

Where Your Checking Stops

Tier 1 · Site check

Running the reset test, observing the light, counting pulls off invoices, photographing the container.

Tier 3 · Service technician

Anything inside the control cabinet — testing or replacing the pressure switch, relay work, and PLC diagnosis. 480V is present in that enclosure.

Do not crack a fitting to check for pressure

Stored hydraulic energy is the hazard that makes this Tier 3 no matter how simple the repair looks. Loosening a fitting “to see if there’s still pressure in it” is how people get injection injuries — which do not look serious for the first hour and are a surgical emergency. Pressure gets relieved deliberately and confirmed at the gauge.
Questions We Get

False Full Signals, Answered

Could the container actually be full and just look empty?

It can. Bridged material leaves large voids while the chamber genuinely cannot take more, which reads as full to the machine and empty to the eye. If the ram is reaching pressure against bridged material, the machine is not wrong — the load pattern is.

Plenty of sites end up doing exactly that, and it works until the day the container is genuinely full and nobody believes the signal. Overfilling is what warps container doors and what makes them stop latching.

It is one of the cheaper parts on the machine. What costs money on this fault is the diagnosis to confirm it is the switch rather than the relay or the logic, and the months of extra hauls before anyone looks.

It changes who notices, not what is wrong. If the monitoring integration takes its signal from the same pressure switch, a bad switch makes the reports wrong too — with the added problem that everyone now trusts a dashboard instead of looking at the container.
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T&T Weber Hydraulic Inc.
184 Stone St, Unit 5
Clinton, MA 01510

Where we go

Onsite compactor and baler service throughout New England — Massachusetts, Connecticut, Rhode Island, New Hampshire, Vermont and Maine. Cylinder reseal and replacement, domestic replacement cylinders, hydraulic, electrical and controls, and full mechanical repair.