The No Fault Found Visit SOP
Purpose
To make a no-fault-found visit a controlled, repeatable outcome with a defensible record, rather than the default result whenever a tech does not find something in the first twenty minutes. This SOP covers the whole path: what the office collects before dispatch, the minimum observation the tech owes the complaint, how the verdict is assigned, what the customer is told, and how the shop reviews the pattern monthly.
The measurable outputs are a lower repeat-visit rate on the same complaint, and a record on every one of these visits that the next tech can start from instead of starting over.
Scope
Applies to every diagnostic visit where the reported complaint is not confirmed as an equipment fault during the visit. This includes correct operation the customer misread, intermittents that did not occur while the tech was present, and complaints traced to a customer-supplied consumable or a household change rather than the equipment.
Does not cover the billing decision itself (see the existing no-fault charge, waive, or monitor guidance), warranty determination, or scheduled maintenance visits with no complaint attached.
Definitions
No fault found (NFF). A visit closed without a confirmed equipment fault. Under this SOP it is never a final verdict on its own and must resolve into one of the three findings in step 7.
Heat soak. The state where component temperatures have stopped climbing under continuous operation. Typically reached somewhere between roughly 20 minutes and about an hour, longer for systems with significant thermal mass such as a large water volume or a heavy motor frame. Confirmed when a repeat reading five minutes later has stopped moving in one direction.
Live-dead-live. Proving a meter on a known live source, proving the target circuit dead, then proving the meter still live. The only acceptable method for verifying absence of voltage.
Discriminator. The additional test that moves an ambiguous observation into a column: timing within the cycle, trend across a run, comparison against an identical peer, or persistence after shutdown.
Roles and responsibilities
| Role | Owns |
|---|---|
| Office / dispatch | Intake triage, verbatim complaint capture, remote observation request, dispatch-or-triage decision |
| Technician | Hazard state, minimum observation runtime, discriminating tests, verdict assignment, customer demonstration, record |
| Service manager | Weekly spot-audit of NFF records, monthly rate review, coaching on miscoded verdicts |
| Owner | The NFF rate threshold that triggers a review, and any change to the minimum runtime standards |
Procedure
1. Capture the complaint verbatim at intake. Office records the customer's own words in quotation marks, unedited, including the vague parts. Do not translate at intake. The verbatim quote is the only anchor when the complaint changes shape across later visits.
2. Ask the trigger question. Office asks: "What changed around the time you first noticed it?" Record the answer. A recent service visit, a season starting, a new occupant, a self-replaced consumable, or a neighbour's failure each point the visit in a different direction, and this one question resolves a meaningful share of these calls before a truck moves.
3. Request observations, not conclusions, before dispatch. Office asks for what can be observed without tools: how long it lasts, how often, whether it stops on its own, what time of day, whether anything is warm that was not before. Where the customer is willing, request a short video with the sound recorded, or three cycle timings taken with a phone stopwatch. Never accept the customer's diagnosis as a fact to be dispatched on. "The motor is straining" is a guess wearing technical vocabulary.
4. Make the dispatch-or-triage decision. Any report involving gas, combustion products, a burning smell, smoke, shock, water contacting electrical equipment, or an occupant symptom is dispatched immediately with safety instructions given on the call, and is never triaged remotely. Everything else may be held for a remote observation set first, with the criterion stated to the customer in advance: what result means a visit is scheduled and what result means it is normal.
5. Set the hazard state on arrival, before any diagnosis. Anything capable of automatic restart is locked out, not switched off. Electrical work gets live-dead-live at the point of contact. Stored energy is discharged and verified at zero. Pressurized systems are isolated and relieved before any joint is opened. Where a real hazard was reported, the safety action taken is the first line written into the record.
6. Meet the minimum observation runtime for the complaint type. These are the shop's defaults; tune them to your equipment mix, but do not close a visit under them without the service manager agreeing.
| Complaint type | Minimum observation before a verdict may be assigned |
|---|---|
| Noise | 3 complete cycle transitions, startup and shutdown both observed |
| Cycling or run-time complaint | 3 complete cycles logged with run and off durations |
| Heat, smell, or performance loss | Run to heat soak, minimum 45 minutes continuous, with a cold reading set and a soaked reading set |
| Water or moisture | One full cycle plus a persistence check at least 30 minutes after shutdown |
| Intermittent, any type | 60 minutes continuous or 3 complete cycles, whichever is longer |
7. Apply the discriminators and record what each ruled out. For every theory tested, write one line naming the theory and the specific observation that eliminated it. "Checked wiring, OK" does not satisfy this step. "Intermittent termination ruled out: three occurrences spaced within a few percent of the same interval, which is control-driven regularity" does.
8. Assign one of three verdicts. A bare "no fault found" is not an acceptable closeout under this SOP.
| Verdict | Criteria |
|---|---|
| Conforms to design | Cold and soaked readings both inside a stated target, trend flat, cycle behavior in band |
| Conforms with an observed trend | All readings inside tolerance but one walks in a direction across the run, or a peer comparison shows asymmetry inside limits |
| Complaint not reproduced | The reported behavior did not occur during the visit |
Coding an unreproduced intermittent as conforming is the most damaging error available in this SOP, because it converts an open fault into a closed one in the file and hands the next tech a false clearance. It is treated as a documentation defect in the audit, regardless of what the system later turns out to be doing.
9. Demonstrate the finding to the customer. State the test and the expected result before running it, so the criterion is agreed in advance and falsifiable in front of them. Show one reading against its target, with the target's source visible. Where safe and reversible, show a contrast case so the customer has a scale for the reading. Bystanders stay at a stated distance from any energized, pressurized, or hot equipment, and do not approach at all where combustion, stored pressure, or height are involved.
10. Give a written escalation trigger in the customer's language. Specific, observable without tools, framed as a threshold. "Call if it gets worse" does not satisfy this step. Name the frequency, duration, or condition that means the behavior has changed state. The same wording goes in the customer's copy and in the shop record.
11. Close the record with the required fields. Verbatim complaint, translated observable, safety action taken, target and its source, at least two reading sets each stamped with elapsed runtime, theories ruled out with what ruled them, the assigned verdict, the escalation trigger, and any photographs of conditions that were altered or cleaned. Photograph before cleaning, always; once wiped, the evidence is gone permanently.
12. Hand the billing decision to the existing policy. The tech does not improvise the charge conversation on the doorstep. Record the outcome and the time on site; the charge, waive, or monitor call follows the shop's standing policy.
13. Spot-audit weekly. The service manager pulls two NFF records at random each week and checks them against the required fields in step 11. This is a documentation audit, not a second-guess of the diagnosis.
14. Review the rate monthly. The shop's standing threshold is that NFF visits above 15 percent of diagnostic calls in a month triggers a review. Tune that number to your work mix, but set one, because a rate with no threshold never gets examined. The review looks at three cuts: which behaviors are producing the volume, how many came from systems the shop installed within the last 12 months, and how many records failed the audit.
Worked example of the monthly review
One month, 96 diagnostic calls, 18 closed NFF. That is about 19 percent, above the 15 percent threshold, so the review runs.
Record audit on all 18. Five had only one reading set with no runtime stamp, about 28 percent. Seven had no written escalation trigger, about 39 percent. Three were coded "conforms to design" on complaints that were never reproduced during the visit, about 17 percent, which is the defect that matters most and the one that goes straight to coaching.
Behavior cut. Eleven of the 18 traced to a transition noise, a scheduled interruption cycle, or condensation. That is not a diagnostic problem, it is a handover problem, and it points at the customer briefing rather than at the techs.
Origin cut. Six of the 18 were on systems this shop installed within the previous 12 months, and none of those six had a behavior briefing recorded at handover. Those six are the cheapest ones to eliminate, and eliminating them is a change to the install checklist, not to the diagnostic process.
Actions from the review. Add the behavior briefing to the install closeout so it cannot be marked complete without it. Coach the three miscoded verdicts individually, with the distinction between "conforms" and "not reproduced" stated explicitly. Add the escalation trigger and the runtime stamp as required fields the closeout will not submit without.
The point of the review is that 19 percent is not a number to feel bad about. It is a number that decomposes into a handover fix, a coaching fix, and a form fix, none of which would have been visible without cutting it three ways.
References
- OSHA lockout/tagout requirements for equipment capable of automatic restart during service or observation
- NFPA 70E live-dead-live verification practice before contacting any conductor or terminal
- Manufacturer documentation for rated operating ranges, documented cycle intervals, and consumable specifications
- See related: How to Document a No Fault Found Visit Defensibly; How to Verify a System Is Operating as Designed; No Fault Found Charge vs Waive vs Monitor Decision Matrix