I ran a service call today with another tech where the previous tech had diagnosed an intermittent piston restriction. I read the history beforehand and for the past several years there were a lot of assorted comfort complaints and lot of little charge adjustments in both the Summer and winter, it is worth noting here the system, like many in our market this system a heat pump.
There were mentions of freeze-up during the Summer and high pressure cut out during the Winter which had me thinking airflow even before we arrived.
As we pulled up I noticed it was a townhome community with four homes per building.
There was no tenant home so we accessed the home via lockbox and as we walked up the stairs I was noticing the home was quite small… two bedrooms and two baths and when we opened the air handler closet it was….. 3.5 tons
The place had 12″x12″ tiles on the floor and it was a simple rectangle so we counted up length x width and the entire home was just under 1200 sqft.
Now sqft per ton is no way to do a load calculation… I admit it
But this townhome had occupied spaces on both sides meaning the only exposures and windows were on two sides with big trees shading the back, the building was built in 2007 and this system was installed in 2016.
What's the next move you would make?
The great thing about having 4 other, almost identical units on the building is that we can easily see what tonnage they had installed, and they were 2-ton units…. makes more sense.
So in 2016 some fly-by-night company hacked in a 3.5-ton unit rather than using a 2-ton that may have been a little oversized to begin with given the low loads on this home.
The result is a system that is running REALLY low airflow resulting in low evap temperature and low superheat in the summer and high head pressure in the winter. Techs had been trying to “fix” the problem each year with little charge adjustments rather than finding and fixing the underlying issue.
After walking around the home we found some vents closed… likely because they were blowing somebody's wig off with the high air velocity.
We went in the attic and found some ducts unsealed, some insulation pushed out of the way and two bath fans venting freely in the attic.
None of this required fancy tools or advanced diagnostic techniques to diagnose… just some common sense… some looking around and a little comparison to figure out the story.
This is the tale of how I found myself stuck on a service call for over 12 hours on a weekend, due to my failure to re-diagnose an issue. I was working for a service company that had many accounts with local gas stations. These were large customers, and we did everything we could to keep them happy.
One Friday as I was gearing up for my on-call weekend, I was informed I must travel an hour and a half away early the next morning to a gas station where another technician had diagnosed a faulty X-13 blower motor. The technician didn’t have the right blower motor for the repair, so the system was still down. The catch was: no one knew what size blower motor was supposed to go in. No model numbers, no detailed notes, nothing. So I grab every size aftermarket X-13 motor I could find in the shop. I had up to ¾ HP.
I arrived to find this location had two 5-ton package units mounted atop stands lifted 8 feet off the ground. After I setup the ladder and double-check the motor size, I realized it was 1 HP. I began calling all the parts houses in the area, hoping someone answered on a Saturday morning at 8am. No luck. I called parts houses in my local area and my co-workers to try and find a 1 HP X-13 motor that would work. Finally, I got in touch with one of my local suppliers. He had a motor that would fit the system I was working on, but he was an hour away from the supply house, and I was an additional hour and half away. Luckily, my employer at the time picked it up for me, and I had the part within a couple hours. I still had not re-diagnosed the system at that time.
Once I had the motor in hand, I quickly replaced it and had everything back together in a snap. I re-energize the system and….I curse loudly. The motor wouldn’t run. NOW I start re-diagnosing, a step I should have taken when I first arrived. Turns out, the original motor was just fine. The motor was not receiving 24v to the motor module, due to a faulty fan relay. I swapped out the 90-340 relay in the electrical compartment, restarted the system, and the blower ran beautifully. I hated myself.
I entertained the idea of packing up, walking away, and calling it complete, but I knew too well how that plays out. I began running complete system diagnostics, and found the system charge to be very low. I started leak searching the system with Big BlueⓇ from Refrigeration Technologies, and discovered a micro leak on the mechanical connection between the distributor tube and the TXV. No rubs outs were apparent, and it wasn’t a super loose connection, but it was clearly leaking. This was a package unit, remember, so I had to recover the entire system charge before I could make any repairs.
Once recovered, I found the connection was just coming loose. A healthy dab of NylogⓇ on the fitting connection and a torque wrench was all I needed to pass a nitrogen pressure test. Of course, the repair process was time-consuming, but eventually, I had the system evacuated, cleaned, recharged, and operating in peak condition under the current load.
I still would have needed to make the leak repair no matter what, but I could have easily saved 3.5 hours of time if i had re-diagnosed the system first when I arrived to the job. One could argue I was simply distracted by the chaos of the call, which would be true. However, a good technician should be able to follow the proper processes in spite of disorganization and frustration. I learned the importance of always checking behind yourself and others when you arrive to make a repair. Since, I have found the real causes for issues that were previously (either by me, or another technician) diagnosed as bad TXVs, reversing valves, motors, etc.
ALWAYS double-check your work and other people’s work. You never know how valuable it is until you fail to do it, and it costs you time and money.
When you walk up to a piece of equipment you want to follow a process to ensure that you accomplish five things.
#1 – You diagnose the fault correctly
#2 – If possible you find the “why” of the failure
#3 – Find any other problems or potential problems with the system that can cause inefficiency, low capacity, failure, safety or indoor air quality issues
#4 – Communicate clearly with the customer and and office about these issues via paperwork and / or verbal communication
#5 – Execute and repair the issues in an efficient and workmanlike manner
In order to accomplish this I recommend looking at the equipment with a wide, narrow, wide mindset
First, speak with the customer, read the call history, understand any concerns the customer may have and any past failures. Look at the equipment, look for any obvious signs of issues like oil stains, corrosion, rubbing wires, bloated capacitors etc…
Then go narrow and FIND THE CURRENT PROBLEM. The difference between a “Sales Tech” and a real service tech is the ability to quickly and accurately diagnose the problem at hand as well as find the likely causes of the failure.
Finally, once you find THE problem, go wide again and look for any other problems BEFORE communicating with the customer. Look at coils, contactors, capacitors, filters, belts, wire connections and potential rub outs, check coils and accumulator for oil stains etc…
When looking wide take the mindest that..
– The system was likely installed poorly / incorrectly to begin with
– Every other repair made to the unit was done improperly
This will put you in the mindset to double-check everything.
Now you are ready to talk to the customer and make repairs with confidence.
WARNING: THIS ARTICLE CONTAINS GENERALIZATIONS. IT DOES NOT APPLY TO EVERYONE AND WE HAVE ALL PROBABLY BEEN ALL OF THESE AT ONE POINT OR ANOTHER. IF YOU FEEL PERSONALLY ATTACKED MAY I SUGGEST FINDING A SAFE SPACE AT A WEST COAST UNIVERSITY AND BORROWING A BINKY FROM A NEARBY TODDLER. ALSO… MY CAPS LOCK BUTTON IS STUCK.
It was my first few weeks out of tech school and I had already ridden with several guys. Some good, some not as good but today was the first time with this tech and something was already different. We were driving to our first call of the day and between dirty jokes and puffs on a cigarette.
“OK, let's guess what's wrong with this next one… they are all Lennox in this subdivision… so I'm betting…. a TXV”
That was my first exposure to the “Been there, seen that” tech, that relies on calibrated guesswork as a primary diagnosis tool. Along the way I've met many more of these and other types of techs in the “Diagnosis Pyramid” and so… I will share them with you now.
I confess I stole this pyramid idea from “Grahams Hierarchy of Disagreement” which is also one of my favorites… maybe I just like pyramids, my grandmother was an ancient alien so there's that.
I literally just made a podcast where I said we should stop calling people hacks. So I guess I'm a hypocrite, but hack is much easier to say than “tradesperson of dubious skills, training or intellect” so hack will need to suffice here.
Many hacks think they know what they doing because they suffer from a heavy dose of Dunning-Krueger effect and are standing firmly on Mt. Stupid as shown here.
The good news is that many confident people start here and this is not a life sentence to stay stranded on Mt. stupid. I have done complete hack jobs in my career, thinking I had enough skill, knowledge and experience only to realize later that I was a bumbling goon. The hack has to travel through the valley of despair to reach the slope of enlightenment where they can become a real tech.
Strength = Ignorance is Bliss
Fatal Flaw = They Are Terrible at Working on HVAC/R
Let's start by focusing on the good things about a white shirt:
They smell nice
They have a firm handshake
They rarely break systems because they don't use tools on them very often
Truth is that many good techs could learn a thing or three about positive communication and people skills from a white shirt, but that is where my positive comments end.
The trouble with white shirts advancing beyond that stage is they have no incentive to do so. They don't need to get dirty, they make lots of money and they look dang good doing it.
These are just salespeople and the more they learn technically, the more complicated it can be to sell systems so why bother?
Strength = Making Money & Looking good
Fatal Flaw = Greed
There are two types of parts changers, the one who does it to make more money and the one who does it because he thinks that's what diagnosis is.
In flat rate environments that pay bid time or commission on parts there are techs who catch on quick that certain repairs are money makers so they look EXTRA HARD for those repairs on every job. It isn't to say they are purposefully looking to pad a ticket but they become fixated on certain things that bring in the most money to them.
The other parts changer is often an inexperienced or under-trained tech who throws a bunch of parts at a problem and honestly thinks that's how you fix problems.
I knew one tech that would replace the control wire and transformer every time he a low voltage fuse blowing that he couldn't figure out. He didn't do it because it benefitted him in any way, he just didn't know how to troubleshoot.
Strength = They Eventually Get The System Running (Mostly)
Fatal Flaw = It Costs a Lot and Often Requires Multiple Trips
Been There Tech
The been there tech is common in all industries and is especially in techs who have done the job 10+ years. When you start out as a hack or a parts changer it's often easier to end up relying on what you've seen before than it is to go back to the start and really understand the fundamentals of how things work.
It can be a big ego hit for a been there tech to admit what they don't understand so they often form complex legends to explain why things happen the way they do.
Been there techs will often talk about “weird problems” and will concoct strange solutions to problems such as drilling holes places you are pretty sure they shouldn't or wiring this or that to that other thing or bypassing that one part because “it's not really needed”.
The been there tech should do more manual reading and less storytelling and they will find the myths and legends begin to look more like science.
Strength = They Often Have a Lot of Valuable Experiential Knowledge
Fatal Flaw = What They Know Only Applies to What They've Actually Worked On. New Technology is Often Confounding.
The final four techs are all truly techs and they have more in common then they have that separate them. The majority of the techs you meet that can actually repair most problems on most machines are average techs.
An average tech generally knows how the system works, can use a gauge manifold and a meter and can figure out the location of a leak or a low voltage short.
Their focus is on diagnosing the primary problem, fixing it and getting out of there as quickly as possible. They don't do much with superheat or subcool though they know how to calculate it, they don't use a micron gauge though they know the “right” answer is 500 microns and they don't really care to learn much more.
Strength = They Can Consistently Make Stuff Blow Cold and Hot
Fatal Flaw = Callbacks are Pretty Common When “More Stuff Breaks”
A real senior tech has all the find and fix skills of an average tech but with extra insight as to the “why” behind a failure. Yes the TXV is restricted but WHY wasn't the factory drier replaced with a new one when that compressor was replaced 6 months ago?
A senior tech knows how a compressor works and what makes it fail, knows how to check combustion on a furnace and what is causing the rising CO and can spot a leaking flare fitting from a mile away.
The thing that keeps a senior tech from becoming a Supertech is the vision of more than one layer beyond the NOW cause to all of the contributing factors that are often outside of the equipment itself.
Issues like high a low humidity, sweating ducts, occupant discomfort, coils that keep leaking over and over, consistent compressor failures when all the readings look “fine”.
When issues start to spread outside of the equipment into the electrical system, indoor air, envelope, ducts and design a senior tech can find themselves frustrated.
Strength = Excellent Diagnosticians
Fatal Flaw = Appliance Fixation
The term “Supertech” is often used as a pejorative to mean an experienced tech who thinks they know it all. These types of Supertech are often actually “been there” techs who like to talk on social media.
No, here I'm saying supertech as in a tech that can really fix just about anything with enough time alloted. They are nerdy enough to fill any knowledge gaps they may have about an issue before they call it good. They diagnose the entire structure and notice all of the contributing factors to problems. You can throw this sort of tech at almost any problem…. however…
They still are all about solving problems and can miss opportunities to optimize performance.
Strength = They Can Fix Anything
Challenge = They Aren't Always That Profitable
Ok… I'm stretching here, but let's face it… this whole thing is a bit of a stretch.
In order for a really good tech to also optimize profitability, they need to look outside of what is wrong in need of fixing and what can be improved for optimal
Indoor Health & Safety
Doing this really well is a heck of a lot more than just selling a UV light or PCO like many white shirts do, it's about really understanding how to tune a building and equipment to work better.
This is things like dropping the compression ratio on a rack by letting the head float a little lower, or recommending that can lights be replaced with sealed led trim to reduce attic infiltration.
There are many high-value solutions that HVAC/R techs can help to suggest and implement that lead to a profitable business and happy customers.
Strength = Living Happily Ever After
Fatal Flaw = Too Much Money that They Must Build a Tower Like Scrooge McDuck to House (Ok, more like pride in their work and good nights sleep…. leave the gold tower to the white shirts)
You've probably heard the famous last words “Dude, watch this” before a concussion, burn, shock, broken bones or some other bodily harm. This phrase has become synonymous with young guys doing something dumb to impress their friends.
Technicians have two common phrases that may not lead to bodily harm (although sometimes it might) and they are –
“That's Good Enough” and “That's Normal”
Pulling a vacuum for 30 minutes without a micron gauge and then “That's good enough”.
Doing a standing pressure test and the pressure keeps dropping JUST A LITTLE and “That's normal”.
Running a 0 superheat and “I see that all the time” followed by some made up reason about this particular equipment, or load conditions.
I have heard lot's of made up explanations over the years… some of them out of my own mouth and almost all of them being used as a justification for something being good enough or normal.
Don't misunderstand, normal and good enough are both real concepts, but they need to be backed by deep understanding of the equipment you are working on (have you read the entire installation instructions and / or service manual?) and the readings you are taking (Do you understand what they mean, why you are taking them and how your test instruments / tools work?).
If you can't follow it up with “It's normal because…..” or “That's good enough because….” with a real answer, not a made up reason, then you need to keep working.
This is a journey for all of us, but stop for one second and be honest with yourself. When you get frustrated, short on time or feel in over your head… Do you ever use these phrases? If so, congratulations. You are in an elite group of techs willing to admit what you don't know.
Now repeat after me…
“I will no longer make excuses for what I don't understand, I will stop and work to understand what is actually going on until I have it mastered”
P.S. – Sorry for the repeat after me thing… It's a bit too much, but this whole article is nerdy as heck so I figured I would just take it all the way.
A good technician uses their senses before they use diagnosis tools. Is your suction line abnormally cold? Make sure the evaporator coil isn't frozen and inspect for obvious airflow issues like a dirty filter or evaporator coil.
Is your liquid line abnormally warm to the touch? Could be a dirty condenser, condensing fan issue or overcharge.
Listen for abnormal motor and compressor noises, watch for signs of corrosion and oil for possible leaks.
Smell for signs of burning lacquer which can signal burned motors or controls.
Listen for a blower that sounds like a train engine (If it's an ECM it could be an airflow restriction) .
Train your senses to spot abnormalities and you will save time and catch issues before you need to pull out tools for confirmation.
This isn't to say that you shouldn't use diagnostic tools, just that you will save a lot of time if you use the best tools of all first.
This article is part 3 in a 5 part series by Senior Refrigeration and HVAC Technician Jeremy Smith
Let's start with Step#1 in the flowchart.
This is why we spend money on those fancy digital manifolds, shiny electrical meters and other gadgets, widgets and doodads. It isn't to brag about them on Facebook, it's to find problems better and faster than someone else.
So, before you start trying to change things, start by gathering and recording data. Inspect filters, inspect coils. Look over the wiring. Check your voltages, resistances, airflow, pressure readings, temperature readings. Locate any open switches in the control circuit and try to determine WHY that switch is open. A pocket notebook is nice but, for larger problems, I've taken to carrying a full sized college type notebook.
This gives me more room on the page to write my notes, draw pictures, scribble thoughts and observations about the equipment I'm working on.
Write down every measurement and reading. EVERYTHING. Even if you find that capacitor blown up and you “just know” that's the problem, take your time and keep looking.
Before we leave the Data Gathering step, we do need to take whatever steps are necessary to get the equipment running if it isn't already and gather another set of data
Once you have all this data together, we can proceed to Step #2. Analysis.
This article is the second in a 5 part series by Senior refrigeration and HVAC tech Jeremy Smith
The Ground rules
I've spent some time thinking about troubleshooting and the processes and procedures that
I use to find problems. Not the “why isn't my air-conditioner running?” problems but the “Things
just aren't quite right.” type problems. The really difficult ones.
I've boiled it down to a sort of flowchart to simplify things and we'll take the flowchart
step-by-step, explaining each step as we go along.
Something to keep in mind as you read this. There is no step by step, color by numbers guide
to troubleshooting. I'm not trying to give you a magic wand to wave at broken air conditioners
because such a thing doesn't exist. Troubleshooting is more of a “can do” attitude combined
with experience and some applied critical thinking. First thing, let's start with a couple of “Dont's” when troubleshooting.
#1. Don't rush
Yes, I know that many of us get piled up under a load of calls and can
be pressured to rush through them to get home to the family. Yes, I know the boss or dispatcher (or both) are calling
you every 10 minutes asking if you're done and ready to move. Yea, I know the customer is
breathing down your neck to get the machine running. This is probably the hardest part of
troubleshooting. You NEED TO block that stuff out. You need to take your time and work
through the problem methodically. #2. Don't assume
Follow your troubleshooting procedure through to the end. Taking
shortcuts is almost as bad as allowing yourself to be distracted.
Over the course of a couple of articles, I'm going to share my troubleshooting processes and
procedures and hopefully give you some tips to build a process that will help you to be better.
This article was written by Senior Refrigeration tech Jeremy Smith. Big thanks to Jeremy for his contributions to HVAC School and the tech community.
Having spent many years in the trade and many years reading posts from techs on forums and social media, a big issue that I see is that troubleshooting is something of a lost art.
Troubleshooting is where the rubber meets the road for a service technician. Nobody cares what certifications you have, what union you belong to or anything else. If you can't find the problem and solve it in a timely fashion, your customer and employer are not going to be happy.
One of the things that I think most guys struggle with is the mental aspect of troubleshooting. I'll relate this in the form of a recent call I was sent on to “clean up”. It was a no heat call in a small convenience store. Trane RTU on a zone sensor.
The tech called me and related that the unit had a call for heat at the unit but the ignition sequence didn’t start. We talked a little about the problem, he checked some limits and a few other things. He wound up ordering an Ignition board and limit sensors. These were replaced late that night and the unit still didn't work.
I was sent the next morning. Now, we get into the mental part of troubleshooting.
I met the tech so that he could communicate the basics of what he did. We talked for about 10 minutes and he went on to his job and I went to have a chat with the trouble unit.
20 minutes later, I had the problem solved. I found a failed RTRM board. Now, you guys that do Trane all the time probably aren't surprised, but let's analyze what went wrong and how this could have been handled on a “one stop” basis.
What did I do that the first Tech didn't?
For starters, I took everything that I was told about the unit, what it was and wasn't doing and what everybody and their brother thought was wrong with it and I threw it all out. Put it in a box in my head, closed the lid and locked it.
I dug out the basic Trane “Service Facts” book and started the troubleshooting procedure from Step 1 and followed it to the end.
Now, I can make these arrogant claims about how I'm a Billy Badass service guy and how I'm more awesome than anyone else, but the simple fact is that I'm not. I do things a little differently and think a little differently than many others and that sets me apart.
What did the first Tech do wrong? While I'm not in his head, I think that he focused on why the heat didn't work instead of taking the unit AS A WHOLE and diagnose it as a whole. Kind of like the guy who can't figure out why the fridge is warm and spends an hour working on it only to find the plug pulled.
So, the the mental aspect of troubleshooting cannot be ignored.
Start at the beginning, work the process and troubleshoot the entire system. Being willing to read the manufacturers troubleshooting info isn't a newbie move, it shows maturity.
Work on the troubleshooting mindset, don't be a parts changer.
This article was written by Senior Refrigeration Tech Jeremy Smith. Before we get to it I want to remind you that ALL of the tech tips are available in alphabetical order HERE – it's a great link to share with other techs, HVAC business owners, Trade school students etc… you can feel free to share these anywhere.
Alright, maybe “advanced” isn't the right thing to call this little tidbit, maybe it should be “troubleshooting and information sharing in the digital age….”
Microprocessor controls, PCBS, PLCs, call them what you will, electronic circuit boards have become an integral part of the HVAC/R world. From a small heat pump defrost board to an advanced building automation system, these little pieces of equipment seem to be the bane of a techs existence.
One very important thing to remember when working on a system with one of these items installed is that each one has a specific troubleshooting procedure and its own sequence of operations.
So, how is a tech supposed to remember all of this stuff?
Chances are good that you're reading this on a smartphone or a tablet. With that and a couple of free apps, you can build a library of tech manuals, reference documents and other information to allow you to be better at diagnosing problems on specific equipment.
So, how do we build this? Well, you can go Old School and print out all of the manuals and store them in your service truck, or we can keep up with the times and go HVAC/R School and put it in “The Cloud”.
Everybody has a Gmail account. Maybe it's your primary email, maybe it's the one you give people that you don't really like so you never hear from them again. Well, with every Gmail.
account comes 15GB of free online storage through an app called Google Drive. Grab the Google Drive app from the app store or play store and, if your Gmail is logged in to that phone, the drive app is already logged in to access your cloud storage. Now, start to “build” your reference library by uploading those PDF files to the drive.
Sometimes this is easier to do on a PC, but it can be done from a phone or tablet as well, it's just a bit more tedious, at least for me. Then, the next time you’re on a job and have to search and find a manual for a piece of equipment you're working on, save it to your Google Drive, too. Before long, you'll have a very
nice library to draw from.
If you're feeling particularly generous, within Google Drive, you can share that information with co-workers and other techs. You can either allow them to contribute to the library or just to view
You know what's better than having a good memory? having good resources. Oh and reading… you pretty much can't be a good tech nowadays if you never read.