Machine Completely Unresponsive — Diagnostic Flow

Plug a known-good lamp or outlet tester into the wall outlet that the vending machine uses. Confirm the lamp illuminates or the tester shows correct wiring.

Expected: Lamp illuminates or outlet tester shows correct voltage and wiring.

Evidence to note: meter-reading

Unplug the machine. Visually and physically inspect the full length of the power cord for cuts, kinks, discoloration, or melted areas. Check the plug prongs for damage or scorch marks.

Expected: Power cord is intact with no visible damage.

Evidence to note: photo

Locate the main power switch on the machine (typically near the power cord entry). Toggle it OFF, wait 5 seconds, then toggle it ON.

Expected: Switch physically clicks into ON position and machine shows signs of life.

Evidence to note: note

If low-voltage supply is confirmed at the controller input but the display remains blank and the machine does not respond, the controller board or firmware may be at fault. Do not replace the controller without completing all previous steps and the replacement guard checks.

Qualified technician handoff: stop before live electrical testing, sealed-system refrigeration work, compressor service, or protected-compartment access unless a qualified technician is handling the work.

Expected: Machine should show signs of life if controller is functioning.

Evidence to note: meter-reading

Unplug machine. Shine a flashlight through the condenser coil fins. If light does not pass through clearly, the coil is blocked. Verify at least 4 inches of clearance around the machine rear and sides for ventilation.

Qualified technician handoff: stop before live electrical testing, sealed-system refrigeration work, compressor service, or protected-compartment access unless a qualified technician is handling the work.

Expected: Light visible through condenser coil fins and adequate clearance around machine.

Evidence to note: photo

Use a soft coil cleaning brush and vacuum to gently remove dust and debris from the condenser coil fins. Brush in the direction of the fins to avoid bending them. Do not use water unless the area can be fully dried before re-energizing.

Qualified technician handoff: stop before live electrical testing, sealed-system refrigeration work, compressor service, or protected-compartment access unless a qualified technician is handling the work.

Expected: Condenser coil fins are clean and light passes through freely.

Evidence to note: note

Close the door on a piece of paper or dollar bill at multiple points around the perimeter. Pull gently — there should be slight drag at every point. No-drag spots indicate a gap in the seal.

Expected: Consistent drag around the entire door seal perimeter.

Evidence to note: note

Plug in the machine and allow it to run for at least 5 minutes. Listen for compressor hum. Carefully feel the compressor exterior — it should be warm and vibrating slightly if running. requiresFieldValidation for expected temperature range.

Qualified technician handoff: stop before live electrical testing, sealed-system refrigeration work, compressor service, or protected-compartment access unless a qualified technician is handling the work.

Expected: Compressor is warm, vibrating slightly, and evaporator fan is moving air.

Evidence to note: note

With the machine running and compressor on, verify that the evaporator fan is spinning and moving air across the evaporator coil. Listen for fan motor noise and feel for airflow inside the cabinet.

Qualified technician handoff: stop before live electrical testing, sealed-system refrigeration work, compressor service, or protected-compartment access unless a qualified technician is handling the work.

Expected: Evaporator fan spins freely and moves air across the coil.

Evidence to note: photo

Unplug machine. Remove any jammed or misaligned products from the affected column. Reposition the product so it sits squarely in the spiral or pusher. Verify the product matches the approved size and weight for that column.

Expected: Product sits correctly in spiral with no binding.

Evidence to note: photo

An unsafe electrical condition has been detected or suspected. Stop all work. Do not attempt further diagnosis. Unplug the machine if safe to do so. Tag the machine out of service.

Expected: Machine is safely de-energized and tagged.

Evidence to note: note

Refrigeration diagnosis has reached the sealed-system boundary. Sealed-system work including refrigerant handling, compressor replacement, and leak repair requires manufacturer-authorized or licensed refrigeration technician.

Qualified technician handoff: stop before live electrical testing, sealed-system refrigeration work, compressor service, or protected-compartment access unless a qualified technician is handling the work.

Expected: Machine tagged for refrigeration specialist service.

Evidence to note: note