First Responder, Military, and Senior Discounts.
First Responder, Military, and Senior Discounts.
The purpose of diagnosis is to determine what is actually wrong with the equipment and why.
Not:
Klein Cooling technicians diagnose through observation, measurement, testing, comparison, and verification.
A diagnosis should be supported by evidence appropriate to the significance of the recommendation being made.
Diagnose the equipment in front of you.
The financial consequence of a diagnosis matters.
A failed capacitor requires appropriate testing.
A compressor diagnosis requires more.
A recommendation to replace an entire HVAC system requires more still.
A complete duct-system replacement requires actual evaluation of the duct system.
A system replacement recommendation based on a refrigerant leak requires evidence that a leak exists.
A recommendation to increase equipment capacity requires appropriate load and airflow evaluation.
The fact that the customer:
does not reduce our obligation to diagnose correctly.
The laws of refrigeration are unaffected by the customer’s credit limit.
The greater the consequence to the customer, the stronger the evidence should be.
Service calls will vary, but technicians should generally follow this diagnostic process.
Determine what the customer is actually experiencing.
Ask questions.
Listen.
Clarify terminology when necessary.
Do not convert:
“It isn’t cooling right.”
into:
“Low refrigerant.”
Those are not synonyms.
Establish the conditions under which the equipment is operating.
As applicable, this may include:
Measurements without operating conditions can be misleading.
When reasonably possible, make the system do what the customer says it is doing.
Observe the failure.
If the failure cannot be reproduced:
Do not invent one.
Document what the customer reported and what the system did while you were present.
Evaluate the basic systems relevant to the complaint:
Not every call requires every test.
Every call does require enough testing to support the diagnosis being made.
Obtain the measurements necessary to evaluate the suspected condition.
Do not substitute assumptions for measurements when the condition is measurable.
Compare measurements against the appropriate reference.
Depending on the measurement, that may be:
Determine what condition or component actually explains the complaint.
A symptom is not necessarily the cause.
Before recommending a significant repair, ask:
Does the evidence actually prove what I am about to tell this customer?
If not:
Keep diagnosing.
Perform the authorized repair according to company procedures and applicable manufacturer requirements.
Operate the equipment.
Verify the repair.
Confirm, as reasonably possible, that the original complaint has been corrected.
Replacing the part is Step 9.
The service call does not mysteriously end at Step 9.
When an actual measurement is relevant to diagnosis, technicians shall record the actual measured value.
Do not document:
Capacitor — good
Compressor amps — normal
Temperature split — fine
Static — okay
Voltage — good
Superheat — normal
Subcooling — looks good
Record the measurement.
Example:
Run capacitor: 43.8 µF — rated 45 µF ±6%
Not:
Cap good
Another:
Return air: 76°F
Supply air: 57°F
Temperature difference: 19°F
Not:
Temps good
Another:
Total external static pressure: 0.74 in. w.c.
Not:
Static high
A number is better than an adjective.
A number with context is better still.
For example:
TESP: 0.74 in. w.c.; equipment maximum rated external static pressure: 0.50 in. w.c.
Now the next technician knows both:
What we measured.
and:
Why it mattered.
Where applicable, measurements should be compared to the relevant manufacturer specification, rated tolerance, performance data, nameplate information, or diagnostic target.
This standard does not require technicians to record every number an instrument is capable of displaying.
Measure what is relevant.
Record what is relevant.
Do not create false precision when operating conditions or the test method do not support it.
When the number matters, use the number.
Measure it. Record it. Compare it. Then interpret it.
“System operating normally” may be an appropriate summary conclusion.
It is not a substitute for relevant diagnostic readings.
Another technician reviewing the call six months later should be able to determine what was actually observed.
Kevin said it was good.
is not diagnostic data.
Kevin may be an excellent technician.
Kevin is not a unit of measurement.
Before becoming emotionally attached to an advanced diagnosis, verify the fundamentals.
Depending on the complaint, this may include:
Do not spend 40 minutes diagnosing a communication failure before discovering the air-handler breaker is off.
Advanced diagnostic skill does not exempt anyone from checking whether the equipment has electricity.
Customer descriptions are valuable diagnostic information.
They are not always complete diagnostic information.
If the customer reports:
“The outdoor unit shuts off but the fan inside keeps running.”
attempt to observe the sequence when reasonably possible.
If they report:
“It freezes every afternoon.”
determine:
Diagnosis improves considerably when the equipment agrees to participate.
An intermittent problem does not stop being real because the technician arrived.
Do not tell the customer:
“There’s nothing wrong with it.”
when the accurate statement is:
“The system is operating while I’m here, and I haven’t been able to reproduce the failure.”
Document:
Do not condemn a component solely because everyone would prefer an answer today.
Components shall not be condemned solely because:
Test the component using an appropriate method.
Suspicion tells you what to test.
Evidence tells you what failed.
Klein Cooling does not diagnose equipment by replacing components until operation resumes.
This procedure is commonly known as:
The Parts Cannon.
It is not an approved diagnostic instrument.
Replacing:
capacitor → contactor → motor → board → thermostat
and announcing:
“Got it.”
after the fifth component does not retroactively make the first four bad.
You have conducted an experiment.
The customer funded it.
There are circumstances where substitution with a known-good component may be a legitimate diagnostic technique.
When used, it shall be deliberate and technically justified.
“Let’s replace this and see what happens.”
is not, by itself, technical justification.
Electrical diagnosis should follow the circuit and sequence of operation.
A useful general framework is:
Depending on the equipment and complaint, verify:
If a motor is not operating, do not immediately condemn the motor.
Determine whether the motor is:
Being told to run.
Receiving what it needs to run.
Capable of running.
Electricity is unusually cooperative in this regard.
Use this feature.
“I don’t think voltage is getting there.”
can generally be improved by obtaining a meter.
Visible burning, melted connections, discoloration, or other physical damage may be significant evidence.
Determine, when reasonably possible, why the damage occurred.
Replacing the visibly damaged component without addressing the cause may create an opportunity to replace the same component again.
We prefer the original opportunity.
Capacitance shall be measured when capacitor condition is relevant to the diagnosis or maintenance procedure.
Record:
Example:
Rated: 45/5 µF ±6%
Measured: 42.9/4.8 µF
Then determine whether the measured value falls within the rated tolerance.
Do not replace a capacitor solely because:
If it is within its applicable specification:
Document the measurement.
The capacitor has passed today’s examination.
Allow it to continue its career.
Before condemning a motor, evaluate the conditions necessary for that motor to operate.
As applicable, this may include:
A motor that is not spinning has provided a symptom.
Determine why it is not spinning before selling a motor.
A control board should be diagnosed through its expected inputs and outputs whenever reasonably possible.
Determine:
A board should not be condemned merely because:
All control boards look weird.
Continue testing.
An error code is diagnostic information.
It is not necessarily a diagnosis.
Technicians shall interpret error codes using manufacturer documentation applicable to the equipment whenever reasonably available.
A code indicating:
LOW PRESSURE
does not automatically mean:
ADD REFRIGERANT.
A communication fault does not automatically mean:
REPLACE THE BOARD.
The code identifies a condition the equipment detected.
Determine why that condition exists.
An error code tells you where to investigate.
It does not necessarily tell you what to replace.
And remember:
E7 means approximately 9,000 different things depending on which piece of HVAC equipment is currently ruining your afternoon.
Read the manual.
Airflow shall be evaluated when it is relevant to the reported complaint or diagnostic condition.
Do not assume airflow solely from:
Depending on the system and complaint, airflow evaluation may include:
A variable-speed blower programmed for 1,600 CFM does not prove that 1,600 CFM is moving through the system under all conditions.
The setting tells us what the equipment is attempting to do.
System resistance still matters.
Or, stated differently:
The board setting is a request.
The duct system still gets a vote.
Airflow directly affects refrigeration-system operation.
Before diagnosing refrigerant charge, metering-device problems, evaporator performance, or other refrigeration conditions that can be influenced by airflow, verify relevant airflow conditions.
Consider, as applicable:
Do not attempt to make precise refrigerant conclusions from a system whose airflow condition is unknown or clearly abnormal when airflow materially affects the readings.
The refrigerant and the air have been working together for some time.
Include both in the investigation.
Refrigerant charge shall not be diagnosed from a single pressure reading.
Before evaluating charge, technicians should verify that the system is operating under conditions appropriate for charge evaluation.
As applicable, consider:
Then use the charging method applicable to the equipment and conditions.
This may involve:
Pressure is a measurement.
Charge is a diagnosis.
Low suction pressure, by itself, does not establish low refrigerant charge.
Conditions capable of affecting suction pressure include, among others:
Determine which condition explains the measurements.
Do not determine refrigerant quantity through intuition.
“Looks about a pound low.”
Based on what?
Did the refrigerant whisper this?
Determine whether the system is undercharged first.
If refrigerant is added, quantify the amount added and verify operation according to the appropriate charging procedure.
Adding refrigerant and observing that suction pressure increased does not, by itself, prove the system was undercharged.
You changed a variable.
Now evaluate the system properly.
If a system is determined to be undercharged, technicians shall not automatically state:
“It just needs Freon.”
Refrigerant does not normally disappear through routine operation.
If a leak is suspected or identified, explain:
Do not state that a specific component is leaking unless evidence supports the location.
Corrosion is not automatically a leak.
Oil is relevant evidence.
Electronic detection is relevant evidence.
Bubble testing is relevant evidence.
Pressure testing and other appropriate methods may be relevant depending on the circumstances.
Use an appropriate leak-detection method for the situation.
A high-superheat condition is not, by itself, a TXV diagnosis.
It is a measurement requiring explanation.
Before condemning a TXV or other metering device, evaluate other conditions capable of producing similar symptoms.
As applicable, verify:
“High superheat” is not a diagnosis.
“Bad TXV” requires evidence.
The TXV is a component.
It is not the HVAC industry’s official explanation for:
“I don’t understand these readings.”
Continue diagnosing.
Equipment shall be evaluated under representative operating conditions when those conditions materially affect the measurements being used for diagnosis.
Removing an air-handler access panel can materially alter airflow.
Altered airflow can alter:
Do not diagnose an airflow-sensitive refrigeration problem from readings obtained under materially altered airflow conditions without accounting for that change.
The system normally operates with the door installed.
This is useful information.
A compressor shall not be condemned until the technician has established why it is not operating or why its operation is unacceptable.
Testing shall be appropriate to the compressor type and reported failure.
As applicable, technicians should:
“The compressor isn’t running” is a symptom.
It is not a compressor diagnosis.
Several components participate in making a compressor run.
Meet them before condemning the most expensive one.
A grounded compressor diagnosis shall be verified using an appropriate test method.
Document the test results.
When appropriate, show and explain the evidence to the customer.
A compressor or system replacement recommendation deserves more diagnostic support than:
“Yep. She’s done.”
A compressor that will not start is not automatically mechanically locked.
Evaluate, as applicable:
“Won’t start” identifies what happened.
Diagnosis identifies why.
Inverter-driven and communicating equipment shall be diagnosed according to the applicable manufacturer’s procedures whenever reasonably available.
Technicians should consider:
Do not apply conventional single-stage diagnostic assumptions to equipment that does not operate like conventional single-stage equipment.
There may be six circuit boards involved.
We did not design it.
We still have to diagnose it.
Manufacturer information should be used whenever equipment-specific data is necessary.
Appropriate resources may include:
There is no bonus for remembering a specification incorrectly.
Look it up.
Google may help locate legitimate technical information.
It does not become the manufacturer simply because it appears first.
Typing:
“Daikin E7”
and replacing the first component mentioned in a forum post from 2014 is not an approved diagnostic process.
Find applicable documentation.
Then verify the condition on the equipment.
If you are stuck:
Ask.
Call another technician.
Call management.
Call manufacturer technical support.
Consult the service literature.
Say:
“I haven’t seen this before.”
That sentence costs considerably less than an incorrectly condemned compressor.
Your job is not to know everything.
Your job is to get to the correct answer.
Another technician’s diagnosis is information.
It is not your diagnosis.
If the customer says:
“The other company said the compressor is bad.”
Test the compressor.
If the customer says:
“The Klein Cooling technician yesterday said it’s the board.”
Test the board.
Yes.
Even when the previous technician works here.
Especially then.
If your findings differ from another technician’s findings:
Explain the technical difference.
Do not automatically conclude:
“They were trying to rip you off.”
Maybe they made a mistake.
Maybe conditions changed.
Maybe the failure was intermittent.
Maybe they had information you don’t have.
Maybe they were simply wrong.
We diagnose equipment. We do not diagnose motives.
Finding one failed component does not establish that nothing else is wrong.
Likewise, finding three aging components does not establish that all three require replacement.
After correcting the initial failure:
Continue testing.
Example:
A failed capacitor prevents a compressor from starting.
The capacitor is replaced.
The compressor starts.
Good.
Well—
6.2 amps.
Now that’s better.
Continue commissioning the system.
After completing a repair, technicians shall verify that the repair corrected the diagnosed condition.
Applicable verification may include:
Replacing the component is not the final step.
Proving the equipment operates correctly is.
Do not replace a capacitor, hear the compressor start, close the ticket, and leave.
The compressor starting is encouraging.
The air conditioner has additional responsibilities.
Verify them.
Additional testing may change the diagnosis.
That is not failure.
That is diagnosis.
Tell the customer.
“Initially I suspected the motor. After testing further, the motor is operating correctly. Here’s what I found instead.”
Do not become emotionally attached to your first theory.
The equipment has no obligation to protect your ego.
If the failure cannot be reproduced:
Document:
Sometimes the correct answer is:
“I cannot prove what is causing this yet.”
That is a legitimate diagnostic outcome.
Replacing something would not make the diagnosis more legitimate.
Sometimes the result of proper testing is:
No repair recommended at this time.
This is allowed.
Do not continue searching until something billable appears.
Do not punish the equipment for passing its tests.
Document what was checked and the relevant readings.
Explain the findings.
Make any legitimate recommendations.
Then leave.
“No repair needed” is a valid diagnostic outcome.
Diagnostic notes shall be detailed enough that another competent technician can reasonably understand:
Avoid:
Chk sys. Bad cap. Repl. Good.
Technically, information has been recorded.
Barely.
Before asking a customer to authorize a repair, ask:
What symptom am I trying to explain?
Did I verify the complaint when reasonably possible?
What did I actually measure?
Did I record the relevant numbers instead of “good” or “normal”?
What should those measurements be, and what am I comparing them against?
Did I evaluate airflow when airflow could affect my conclusion?
Did I verify power, commands, inputs and outputs where applicable?
Am I treating a symptom as though it were a diagnosis?
Am I treating an error code as though it told me what part to replace?
Am I relying on somebody else’s diagnosis?
Does the evidence support the financial significance of what I’m recommending?
Can I explain and, when appropriate, show the evidence to the customer?
Would I be comfortable having another competent technician independently verify this diagnosis?
If yes:
Proceed.
If no:
Keep diagnosing.
Do not guess.
Do not fire the parts cannon.
Do not use “good” when the number matters.
Do not call pressures “normal” when the readings matter.
Do not diagnose low refrigerant from suction pressure alone.
Do not diagnose a TXV from high superheat alone.
Do not condemn a compressor because it did not start.
Do not condemn a board because it looks complicated.
Do not let an error code perform the diagnosis for you.
Do not assume programmed airflow is actual airflow.
Do not ignore airflow while diagnosing refrigeration.
Do not replace something merely because the previous technician said it was bad.
Do not recommend a larger system without doing the work necessary to justify the change.
Do not turn uncertainty into certainty because the customer wants an answer.
Understand the complaint.
Establish the conditions.
Measure.
Record.
Compare.
Isolate.
Verify.
Repair.
Commission.
And when the evidence does not support a repair:
Don’t sell one.
We do not need to be right the first time.
We need to be right before we ask the customer to pay for it.
END OF SECTION 07