The 10 Commandments of the HVAC/R Technician

One trait I've seen with good technicians is that they take their jobs VERY seriously, but they learn not to take themselves too seriously. A few months ago, I had someone tell me online that I must think I'm the A/C “god” because I'm always telling everyone the “right” way to do things. This got me thinking…

I don't want to be an A/C god. That's too much pressure, and heaven knows I've broken all of these rules more than once. I'll settle with being an A/C Moses, descending Mount Sinai with the oracles of truth from on high.

The problems with this metaphor are many, but let's roll with it. The truth is that there are many “prophets,” like Jim Bergmann, Dave Boyd, Dan Holohan, Jack Rise, John Tomczyk, Bill Johnson, Dick Wirz, and Carter Stanfield, who I have taken these “commands” from, and they likely learned these from those that came before them. DON'T build a golden calf to poor workmanship, or we will smash the tablets and make a big mess. Ok, here are the commandments:

1. Thou Shalt Diagnose Completely

Don't stop at the first diagnosis. Check everything in the system—visually first, if possible, and then verify with measurements. Sometimes, you must make one repair before you can do other tests. Still, you can often find the cause of the initial problem and other problems BEFORE making a repair, which helps save time, provides better customer service, and creates a better result.

2. Thou Shalt Not Make Unto Thee Thine Own Reasons

Jim Bergmann often talks about how when techs don't understand something, they start making up their own reasons that something is occurring and then train other techs in these made-up reasons. If you don't understand something, a bit of research and study goes a long way.

3. Thou Shalt Not Change Parts in Vain

In other words, DON'T BE A PARTS CHANGER. Never condemn a part on a guess or make a diagnosis out of frustration. Get to the bottom of the issue, no matter how long it takes. Thorough analysis is better for the customer, the company, the manufacturer, and your development as a tech. If you aren't confident, call someone who is fundamentally sound and get a second opinion BEFORE you leave the site. Better yet, send them a text with all the readings, model and serials, conditions, photos, type of compressor, type of controls, type of metering device, and what you have done BEFORE you call them. Get the diagnosis right the first time.

4. Remember the Airflow and Keep it Wholly

So much of HVAC/R system operation has to do with evaporator load, with LOW load being most commonly caused by LOW AIRFLOW, low airflow being most commonly caused by dirt buildup. Keep blowers, fans, filters, and coils clean and unobstructed. Check static pressure when duct issues are suspected. That way, you can verify and properly set up blower CFM output to match the requirements of the space and outdoor environment.

5. Honor Thy Trainers and Mentors

New techs will often learn a few facts and cling to them as though they are the end-all and be-all of system diagnosis. I have met techs who get over-focused on everything from suction pressure (most common) to superheat, subcool, static pressure, delta T, and amp draw. A good tech continues learning from older and wiser techs and trainers who see the whole picture. When you are new, it's hard to remember all of the factors that go into system diagnosis and performance. More experienced techs who have kept up on their learning develop a “6th sense” that can rub off on you if you “Stay Humble” (to quote the great philosopher Kendrick Lamar). Listen more than you talk, and learn the full range of diagnostic and mechanical skills.

6. Thou Shalt Not Murder The System by Failing to Clean

A good technician learns the importance of keeping a system clean early on and never forgets it. Condenser coils, base pans, drain pans, drains, evaporators, blower wheels, filters, return grilles, secondary heat exchangers, and on and on. A system set up properly and cleaned regularly will last much longer, cool or heat better, and use less energy. In my experience, techs who don't believe in maintenance don't perform proper maintenance themselves. Use your eyes and clean what's dirty.

7. Thou Shalt Not Commit Purgery without Vacuumy

Proper evacuation is one of the most overlooked disciplines of the trade. Jim Bergmann says, again and again, that a proper vacuum is performed with large diameter hoses connected to core removal tools. The cores are removed from the ports, the hoses have no core depressors, and the hoses are connected directly to the pump (not through gauges). The vacuum (micron) gauge is connected to the side port of the core removal tool, not at the pump. The pump has clean vacuum pump oil, and the pump is run until the system is pulled below 500 microns (exact depth depends on the system). The core tools are then valved off, and the “decay” is monitored to ensure that the system is clean and tight.

Purging with dry nitrogen prior to deep vacuum helps with evacuation speed, and installing line driers assists in keeping the system clean and dry. However, neither option is a substitute for a proper deep vacuum and decay test.

8. Thou Shalt Not Steal (from the customer)

Good techs provide solutions for their customers to get a broken system working, and they make other repairs or upgrades that result in optimum performance. Most techs don't INTEND to lie to a customer, but their lack of understanding of the products they are OFFERING—along with strong incentives to OFFER these upgrades—can result in dishonest practices. A good, profitable technician has a deep understanding of all the repairs and upgrades they perform, as well as a sense of empathy for the customer.

9. Thou Shalt Not Bear False Witness Against Other Technicians

This all comes down to a witch's brew of ego and insecurity all mixed together. You have either done this yourself, or you know of someone who has gone to a customer's home or business and thrown the previous technician or company under the bus in front of the customer. In some cases, it may be nothing but bravado, and in other cases, it may have a measure of truth in it (or it may be undisputed). Either way, talking negatively about other techs and companies does nothing but make you look petty and angry. Demonstrate your skill and knowledge by discussing the courses of action you intend to take, and if required, you can COMPARE these actions to previous actions taken; just stay away from personal attacks. Let the customer be the judge about the last guy.

10. Thou Shalt Not Covet Thy Neighbor's Job

Many good techs start to do poor quality work when they get burned out, and buddy, let me tell you—I HAVE BEEN THERE. It is important to remember that every job, from maintenance tech to business owner, has good things and bad things about it. There are good days and bad days, great customers and total jerks, 16 hr days and 8 hr days. You may reach a point where you decide to change jobs, which is totally fine and may be a great decision. Just don't make a rash decision because the grass looks a little greener. ALWAYS do quality work no matter where you work or how bad it gets. Doing poor quality work because your job is getting you down is like cancer that will grow and do harm to you and your career.

Take pride in your work, keep your eyes and ears open, and learn something new every day, and the HVAC/R gods will smile warmly upon you.

What commandments would you add or remove?


P.S. – Neil Comparetto wrote a Ten-Commandments-style tech tip about duct design in “The Ten Duct Commandments (Plus a Few More).” It's an interesting read for those of you who are interested in duct design, and he has provided many good external sources there, too.


Bill Spohn
Bill Spohn
8/6/17 at 01:13 PM

Nice work!
Infomative with a tad of cheekiness!

Calvin Schulz RSE
Calvin Schulz RSE
8/6/17 at 06:06 PM

Wow, this is so awesome and an excellent read. I would like to think that I take all of these very seriously and follow every last one to the best of my ablility.
Every HVAC/R mechanic should have this tattooed on their arms, lol.

Calvin Schulz RSE

Jack hall
Jack hall
8/7/17 at 10:08 PM

Tho shall not borrow others tools eternally

8/8/17 at 10:52 AM

I’ve been a Technician for 35 years. Yesterday was my 54th birthday. All I have ever done is HVAC/R. I LOVE my trade more than most and as I tell my apprentices “Learn your trade !!”
I was told you won’t fully understand our trade until you teach it. To be honest, that is an understatement. I’ve taught the mechanical side, the theory side and the control side. I now realize how much more I can learn.

Keep up the good work and if I can help in any way, let me know.

Robert E. Wolkwitz III

10/9/19 at 11:33 AM

This was perfect.

The only thing I would add is perhaps, don’t be an I know guy. The unteachable technician that always responds with a quick, “I know”.

This is usually the same type of technician that calls someone for technical help but then refuses, refutes or ignores the possible solution for, or likely root cause of whatever issue they are struggling with.


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