How to Return a Suspect Part to the Supplier With Evidence

Why this matters

A part that fails early, measures wrong out of the box, or simply looks off is either a bad lot, a counterfeit, or a part that was damaged somewhere between the factory and your shelf. You usually cannot tell which from the counter. What you can do is send it back in a way that forces the question to be answered by someone who can: the supplier, and through them the manufacturer. A return with a vague note ("bad part") gets a credit at best and an argument at worst, and the shop learns nothing about the rest of the box. A return with photographs, lot codes, measurements and a written list of questions gets an answer, and the answer tells you whether to trust that supplier with the next order.

First, decide whether this is a return at all

This procedure is for a part that is suspect but has caused no damage and no injury. If the part flooded a room, started a fire, shocked someone or is part of any claim, it is evidence, not a return: it stays in the shop under a chain of custody and does not go to any one party's supply chain (see related: How to Keep a Failed Part as Evidence). The two procedures diverge at the first step, so the decision comes before anything is packed.

If you suspect counterfeiting specifically, the units go into the shop's suspect-counterfeit quarantine first, and this return is the outbound half of that process (see related: The Suspect-Counterfeit Quarantine SOP). How to judge whether an electrical component is genuine is its own card (see related: How to Spot a Counterfeit Electrical Component).

The procedure, with one return run alongside it

Most steps below are followed by what they looked like on a real-shaped case, so the numbers carry through. The case: an HVAC shop orders 10 dual run capacitors rated 45 plus 5 microfarads, plus or minus 6 percent, from a supplier it has not used before, because its regular distributor is out. Within 9 days, 2 of them installed on condensing units have failed, both bulged at the top.

1. Stop using the lot, and say so to the whole crew

Pull every remaining unit from the same box, order or lot off the shelf and out of every van. Tag them and move them to quarantine. Tell the techs, in the same message, which lot and what to do if one is already in their hands.

Why: two failures from one box make the rest of the box suspect, whatever the cause. What breaks if skipped: a third unit goes in while the return is being argued about.

Case: the shop had installed 2, and the remaining 8 were still in the shop. All 8 were quarantined the same morning.

2. Make the stored energy safe before handling or testing

Capacitors, springs, batteries, accumulators and pressurized parts can hold energy after removal. For a capacitor, discharge it across its terminals with an insulated discharge tool that has a resistor in it, then confirm zero volts on a meter before touching the terminals; a bulged unit can vent hot electrolyte or oil, so wear eye protection and gloves and keep it upright. For a pressurized part, relieve it per the manufacturer's instructions.

Why: a return is handled by several people who did not remove the part and do not know its history. What breaks if skipped: the person who packs it, or the person who opens it at the supplier, takes the charge.

Case: both failed units were discharged through the resistor tool on removal and proven at 0 volts. The 8 new ones were checked the same way before testing.

3. Photograph everything, including the things that look normal

Each unit: the label face, square on and legible, then the back and the terminals. The lot, date or serial code close up. The packaging: the outer box, any inner carton, the shipping label, any seal or hologram, the printed instruction sheet if there was one. Your invoice or packing slip. Photograph a known-good unit of the same type from your regular source next to a suspect one if you have it.

Why: the details that distinguish a counterfeit or a diverted lot are usually on the label and the packaging, not the part. What breaks if skipped: the supplier receives the parts without the box they came in, and you have nothing to compare them against afterward.

Case: the photos showed something the techs had not noticed: the printing on the suspect labels was slightly blurred at the small text, the listing mark was smaller than on a known-good unit from the regular distributor, and the lot code was the same on all 10 units, including the two that failed.

4. Write the failure description as measurements, not adjectives

State what was measured, with what, under what condition, and against what rating. Include where and when each installed unit failed, from the job records.

Why: a measured value can be checked by the supplier on their own meter in minutes, and it cannot be dismissed as installer opinion. What breaks if skipped: "bad caps" invites the answer "installer error", and you have nothing to point at.

Case: the rated tolerance puts the 45 microfarad section between 42.3 (45 minus 6 percent) and 47.7. The two failed units measured 37.0 and 0 (open) on that section; 37.0 is 8.0 microfarads below rating, about 18 percent low. Of the 8 untested units, 5 measured inside tolerance and 3 measured between 40.1 and 41.6, all below the 42.3 floor. Five of 10 units in the box were out of tolerance (2 installed and failed, 3 new), all from the same lot.

5. Get a return authorization before anything ships

Ask the supplier for a return authorization number (RA, sometimes RMA), which is the supplier's reference for accepting the return. Ask what they need with it: all units or a sample, original packaging, their form. Write the RA on the outside of the package and on every document.

Why: a package without an RA is often refused, lost in receiving, or credited at a restocking rate as an ordinary return. What breaks if skipped: the parts disappear into a warehouse and the shop never hears what was found.

Case: the supplier issued RA 40219 the same day and asked for all 10 units in their original box.

6. Ask the questions in writing, and get the answers in writing

This is the step that turns a credit into information. A phone call is fine to start, but the questions go into an email, and the answers come back the same way.

OFFICE:  Calling about RA 40219, the run capacitors.
         I'm sending the photos and readings now. I
         need a few things back in writing.
COUNTER: We'll credit you once they're received.
OFFICE:  Thanks. Beyond the credit: where did this
         lot come from? Direct from the maker, or
         through another distributor?
COUNTER: I'd have to ask purchasing.
OFFICE:  Please. And can you send the maker's letter
         authorizing you to sell that line? Will the
         lot go back to them for analysis, and will
         we get the result? Last one: did other
         customers get this lot, and have they been
         told?
COUNTER: I'll get purchasing to email you today.

Five questions, every time: the source of the lot, proof the supplier is authorized for the line, whether the parts go to the manufacturer for analysis, whether the shop gets the result, and whether other buyers of the lot are being told. A supplier that answers all five is accountable for what it sells. A supplier that will not answer the first two has told you what you need to know about the next order.

Why: the credit fixes this box. The answers decide whether the next box is safe. What breaks if skipped: you receive a credit memo, reorder from the same supplier, and get the same lot.

7. Ship it so the evidence survives the trip

Pack the units in their original packaging where possible, with the photographs printed or attached, the measurement sheet, the RA, and a copy of your written questions. Use tracking. Keep one failed unit and one untested unit from the lot, tagged, if the supplier agrees, so that you still hold a sample if the analysis is disputed; if the supplier wants every unit, send every unit and rely on the photographs.

Why: a return is a one-way trip for the parts. What breaks if skipped: the supplier says the parts arrived with no packaging, or never arrived, and your only proof left with them.

Case: the supplier wanted all 10. The shop sent them with the photo set and the readings, tracked.

8. Close it, and let the outcome change the supplier list

Record the result: credit, replacement, analysis finding, and the answers to the five questions. Update the shop's list of approved suppliers for safety-critical parts accordingly. If the supplier will not answer, send the lot code and photographs to the manufacturer directly; most makers will tell you whether a lot code is one they produced.

Why: the outcome is what the next order depends on. What breaks if skipped: the shop has paid for the lesson and does not keep it.

Case: the supplier credited the 10 units and said the lot came from another distributor, not the maker, and it could not produce an authorization letter for the line. The shop sent the photographs and lot code to the manufacturer, which replied that the lot code did not match its production records. The shop removed the supplier from its list for electrical and refrigeration parts, went back to both installed jobs to confirm the replacement capacitors there came from its regular distributor, and added the capacitor line to the parts it will buy only through authorized channels (see related: How to Build a Trusted Supplier List for Safety-Critical Parts).

What would have changed the outcome. If the supplier had produced an authorization letter and the maker had confirmed the lot, the most likely explanation becomes a genuine bad lot, and the maker's analysis and any recall notice are the next things to watch for. If only the two installed units had failed and all 8 new ones had measured in tolerance, the installed condition (sustained high heat at the outdoor units, or a voltage problem on the supply) would deserve a look before blaming the part.

References

• Manufacturer data for the part type: rated values, tolerance, and the maker's guidance on verifying genuine product and lot codes.
• See related: How to Keep a Failed Part as Evidence
• See related: The Suspect-Counterfeit Quarantine SOP
• See related: Authorized Distributors and Why the Channel Matters
• See related: How to Build a Trusted Supplier List for Safety-Critical Parts