In this crossover episode Bryan talks with Gary from HVAC Know It All about some of the phrases that techs throw around that are often false.
Trigger Warning: This article isn't specifically about air conditioning and It includes a markedly Christian worldview. If you would rather that I “stick with the A/C stuff preacher boy” then this is one you should skip… or not 🙂 Also, today is my birthday so give me a pass on this one.
Today, families all across the country will gather today to eat too much, watch football and get into a political argument with their uncle or nephew that will lead to yelling in some families and passive-aggressive comments in others.
I don't advise political arguments at Thanksgiving, but if you are GOING to do it anyway I suggest a food fight to top it off, (Hint: The stuffing can be formed into balls and thrown with surprising velocity and to great effect)
One tradition that we often practice on Thanksgiving (on non-food fight years) is to write down things we are thankful for and then take turns reading them out loud (so cliche I know).
It's a nice exercise and I enjoy watching the faces of my mother, mother-in-law, and grandmother, as they listen to their family give thanks, that alone is worth the tradition.
There are many things that always get mentioned -Family, friends, food, our country, God, pets and then a few joke answers like uncle Randy finally give up his comb-over (we are Orr's after all and sarcasm is our love language).
Some things that never get mentioned are hardship, struggle, pain, suffering, sacrifice and hard times
As I thought through what I'm thankful for in the lead up to this Thanksgiving I reflected on a passage in Romans that has been on my mind a lot lately –
These words about rejoicing in suffering were penned by Paul at around AD 58 with the great persecution of Christians by the emperor Nero occurring less than a decade later.
We are talking about a time in history when the very same people Paul wrote this to were fed to lions, crucified and burned on stakes.
I've been through a few tight times in my life, worked some really long hours and been mistreated a time or two but I've never been falsely accused of burning down a city and had my loved ones murdered for what they believed.
We can all agree that there are still guys like me all across the world reading and quoting from people who suffered deeply for what they believed in, something bigger than themselves.
It sounds to me like their suffering has endured just like the passage said.
A Practical Look at Hardship
Fast forward to our modern experience.
The things we complain about and hear others complain about would be beyond laughable to our ancestors.
We can see the results of a generation of parents who tried to insulate their children from hardship and struggle. I grew up hearing people speak of giving their families “what they never had” or providing them with a “comfortable life” with more “free time”.
The result is 20 somethings who look for safe spaces and feel bullied and marginalized when the realities of “adulting” are so viciously forced upon them.
I say phooey to all of that “make life easy” tomfoolery (excuse my use of these words, I always look for openings to use them along with hogwash and poppycock even if they need to be forced in)
Don't worry, this isn't a “kids these days” rant and there is nothing wrong with having a nice life but good doesn't mean an EASY life.
Easy is the enemy of worthwhile
Look at the sequence of events in the passage above
Suffering > Endurance > Character
Tell me that isn't dead-on accurate for people you know who have deep character. If you track backward you will see they have the ability to endure, to stay the course even when it's hard. When you look one step behind that I pretty much assure you there will be a story of struggle, hardship, and suffering to some degree.
Ease Leads to Aimlessness
I was married when I was just 18 years old making $10/hr as a new junior service tech. I always wanted my wife to be able to stay home with the kids and when she got pregnant on our honeymoon that timeline was etched in stone pretty quickly. Those first years of barely scraping by were hard in many ways but the mission of providing for my family was crystal clear.
The same was true when we started Kalos, things were tight and every issue required my personal attention. A few years back things started to get “easier” as there was a team around me and money became less of a struggle. I lost some of the clarity of purpose that struggle provides and frankly… I got soft.
Softness in the mind breeds complaining, whining and entitlement
Softness in the spirit and soul means you start to allow yourself to do things, think about things and become someone that doesn't line up with what you believe is right.
Softness in the body…. is evident to everyone 🙂
Paul says it like this in his letter to the Corinthians –
Therefore I do not run like someone running aimlessly; I do not fight like a boxer beating the air. But I discipline my body and keep it under control, lest after preaching to others I myself should be disqualified.
Hardship and discipline lead to focus and focus can help to keep us from becoming soft of character.
When I think of my children and what I want for them at the deepest level….
It's all character.
The courage to do what is right, the ability to be grateful even when times are tough, the presence to enjoy the relationships around them without distraction.
I want my kids to have endurance and character so I must not rob them of the gift of struggle
Keep the Faith
Rejoicing in hardship… even rejoicing FOR hardship like James encourages us to do in the passage above, only makes sense when we have faith in something bigger than our own temporary suffering.
For me, that's living my life for Jesus and seeking his glory in the largest sense, but there are many other things that also tie into that.
- Serving the HVAC/R trade and working to make it better for everyone involved
- Showing my wife she's the most important person on earth to me
- Teaching my children by modeling character and holding them to a high standard
- Practicing servant-leadership at Kalos
I fail pretty badly at all of these every day but waking up and fighting those battles as hard as I can is the battle I've been given at this stage in my life.
There will come a time when more difficult suffering will come – sickness, injury, big mistakes, the death of loved ones
None of us are making it off of this blue marble alive and pain will always come no matter how hard we strive for ease and comfort.
I don't know about you, but this Thanksgiving I'm going to thank God for hardship and even suffering and I ask that he will grant me endurance and character sufficient to accomplish what I'm called to do while I'm here.
I feel strongly that
We are defined far more by how we respond during hardship than how we behave during the easy times
Our endurance and grace under fire are how we will be remembered. The only way to prepare for it is to steel our minds with the discipline of thankfulness for ALL THINGS not just what we perceive as good.
Happy Thanksgiving and may this holiday season be truly blessed for you and your loved ones.
Proving flame is an important part of the gas firing sequence. Without proof of flame, you risk dumping unspent gas into the heat exchanger resulting in an explosion.
There are many ways to “prove flame” we are focusing on the flame sensing rod (Flame rectification) method here.
Here are the facts-
Flame sensing rods, also known as flame rectifier rods or flame rectification rods are commonplace in modern hot surface and ISI (intermittent spark ignition) gas-fired appliances.
Flame sensing rods stick out into the flame and connect back to the furnace board. Once the board sends a call to the gas valve to open, it monitors the current flow on the flame sensing rod. It does this by generating a potential (voltage) at the flame sensing terminal, this terminal is connected to the sensor with a conductor. When no flame is present there will be potential at the rod and no current, when a flame is present a small microamp (μA) DC current will be present as a path is made between the rod and the ions in the flame. This small DC current signals the board that flame exists and all is well with the world. If it does not sense this microamp (μA) DC current within a few seconds it will shut off the gas valve and try again.
The board outputs this potential (voltage) on the flame sensing terminal right at the beginning of the sequence to confirm that the path is “open” with no flame. This ensures against false positives (sensing flame/current when there should be none) and once it goes from 0 current to the rated microamp (μA) current the board “knows” that flame is present.
These flame sensing rods are “dumb” devices. They do not generate potential (volts) or current (amps), their predecessor the thermocouple (seen in standing pilot systems) does generate a potential itself which is often the source of the confusion.
A flame sensing rod is a piece of metal with a ceramic insulator that keeps it from grounding out. That is all. However, because it is conducting in the Millionths of an amp (microamp) a lot can go wrong with it that a normal electrical component wouldn't have any issue with. Tolerances are tight so small factors make a big difference.
Flame sensors fail when:
- They short out due to a cracked insulator
- They Fail open because they are broken
- They don't conduct because they are not properly placed in the flame
- They become coated in silica (glass) or carbon
Before I go any further I want to address a common question. Do flame sensors have a special coating that can be rubbed off with improper cleaning?
Well… If we are talking about a thermocouple or a thermopile then yes.. absolutely, but we aren't discussing standing pilot systems here.
I have seen a lot of flame sensing rods, and I have done a good deal of research and I have found no evidence that typical flame sensing rods have a special coating on them that can be rubbed off. Now, if you have real, quantifiable proof from a manufacturer that says otherwise.. PLEASE provide it to me so I can retract this statement.
I think it's more likely that issues techs see from cleaning are due to cleaning with sand cloth (Emory cloth) and leaving behind grit that can lead to a coating and poor conductance once heated. I chalk the other part up to confusing a thermocouple with a flame rod and bit to superstition.
Here are the steps to test a flame sensor –
- Ensure the furnace is properly grounded. You can do this by powering down the heater and taking an ohm reading between neutral and the burner assembly. You should read a few ohms of resistance max, the lower the ohm reading the better grounded it is.
- Make sure your polarity is correct, incoming hot connected to hot, neutral to neutral.
- Ensure the rod is positioned so it will be covered in flame
- Get a meter that reads in the microamp scale with a .10 resolution minimum. Use a good QUALITY meter for this and make sure your leads are in the correct locations.
- Connect your leads in SERIES. This means you have to disconnect the lead from the rod, connect one lead to the rod and the other to the terminal to the board WITH THE CONNECTOR UNHOOKED FROM THE ROD
- When the flame lights you should read between .5 and 10 microamps (μA) depending on the furnace. Readings between 2 and 6 are common.
If you do not have a proper microamp (μA) reading you can confirm the following
- That the flame rod is not open. Ohm from tip to the terminal on the rod. If the rod is open it is failed.
- Check the insulator and make sure it isn't cracked or grounded
- Check for proper burner grounding and incoming power polarity (as mentioned)
- Clean the rod… Now, this is a controversial one. I suggest using very fine steel wool or abrasive pad (magic erasers often work). remove and clean the rod and ensure you wipe it clean of any particles leftover from cleaning. Handle very gently. Once complete perform an ohm test from tip to terminal again to ensure you haven't damaged during cleaning. If you want to be really crazy, use some electrical contact cleaner on it after cleaning to help remove any residue… just nowhere near the flame, unless you don't want eyebrows.
Once you have established all of the above and you are still not getting the required microamps then you are left replacing the board.
Word of warning –
Test your tools regularly. If you are trusting your meter and you aren't 100% sure your meter is working and set up properly you may end up with a misdiagnosis. Test and calibrate your tools regularly.
Do every possible test before replacing a board. Many techs advocate just replacing a flame sensor if they suspect it isn't conducting well. I am cool with that so long as
- You don't charge the customer for it is there was nothing wrong with it
- Your company is OK eating the cost of rods that were not needed
Or.. you just install a new one long enough to test. That is all fine and good if you have extra flame rods in your truck. Many techs do not have that luxury.
If flame rods are getting dirty / coated often, you will want to find out why. There is something in the environment or the combustion that is causing it. Many techs notice that furnaces bringing their combustion air from laundry rooms or basements with cleaners nearby often get dirtier quicker.
In Summary, flame rods should be
- In the flame
- Not open
- Not shorted
Now is the part where the furnace techs from all over the world tear me apart.
In this short we discuss the differences between these gases and why only nitrogen is to be used for purging, flowing and pressurization
It doesn't matter if we aligned the belt, dialed in the charge, cleaned the condenser and got the drain pan clean. We look like dummies because the panel fell off.
Also, as you may notice, the insulation also came off.
It doesn't matter if we've had crazy storms or that some of the screws were stripped out long before we got there. What matters is that we serviced it and the panel fell off.
Some of you will roll your eyes that this is even a tech tip. But if you are honest, how many units have you left that didn't have ALL the screws properly in place. How many times have you left a unit where one of them is so stripped out that the screw was doing nothing?
So, the primary message is
Don't leave unless all designed fastening points are secured
This occasionally means tapping in a new screw, sometimes in a new location. Sometimes it may mean running to a hardware store to get a fastener that's lost. Just take care of it properly and take pride in the finished product of your service.
Often it means getting screw with oversized threads to replace ones that are stripped out.
While on the topic keep in mind that screws left on a roof or in the grass can cause roof damage or get picked up by a lawnmower and thrown into a car or another person. It isn't just the panel that comes off that lead to property damage and a safety hazard, it is also the screw itself.
Now… there is something else to consider. The use of impact drivers and drills with no clutch or the clutch set too high has resulted in a big increase in stripped out fasteners.
An impact driver (like shown above) is meant to DRIVE screws either in repetitive or high torque applications. Impact drivers are designed with a “percussion” action that drives screws quickly and forcefully into the base material. That high torque action also does a great job of stripping out screws.
A driver like the one shown above does not have the TORQUE of an impact but it turns screws and fasteners with a smooth motion without the percussion of an impact. It also has a clutch that should be set as low as possible to get a snug fastener without the risk of striping out.
For the average HVAC/R technician, I would advise using a clutched driver as your primary “go bag” tool and only reach for an impact or larger drill if you are driving screws repeatedly into new material.
Using the right tool consistently can make keeping panels firmly in place an easier task and avoid embarrassing situations like the one at the top.
Do you remember the first time you used a ratchet? Neither do I… but I DO remember the context where I first used one.
In order to understand my story with ratchets, I need to introduce you to my grandpa Don, the man who I have always called “Papa”.
My grandpa has done so many jobs in his life that even he can't remember them all in one sitting. When I ask him to give a chronological list he always stops and goes as he's remembering
“Coal miner, scrap collection, welder …. no wait… machinist first, then welder… well driller, plumber, scuba diving plumber, electrician… and the list JUST… KEEPS… GOING.
For as long as I've been alive he has been in the aircraft salvage business, buying or storing wrecked aircraft as well as dismantling them and selling the parts.
Don is a tool guy, but not in an organized or thoughtful way. He buys tools like crazy and throws them all over when done with them. Even today if you walk into his aircraft hangar that doubles as our metal shop you will find mounds of tools piled here and there.
An ironworking machine covered in dust in one corner, a big bead blaster in the other, a cardboard baler abandoned against one wall.
All of these tools bought for a purpose, but likely never used as much as he initially thought they would but don't let the mess fool you… he knows what's there, and we all turn to him when we need a complicated problem solved… even today.
My grandpa isn't an organized person, he's never set foot in a board room or given a powerpoint presentation but he has always charted his own course and owned his own choices one day at a time. At his core, he is a problem solver and there isn't a thing he wants to do that won't get done.
When I was a kid I would come to the hangar every day and listen to the men tell stories about aircraft and complain about the government. I would do little jobs like sort bolts, shred paper or bead blast metal aircraft parts.
But every once in a while… my grandpa would lead me out to a wreck and have me remove some parts, and THIS is where I first got to use a ratchet.
The Ratchet Metaphor
The ratchets my Grandpa had were ALWAYS Snap-on and were smooth as butter to use. I remember the little micro-clicks as the gears worked and it was so fun to remove a bolt or nut from a tight spot, finally releasing an aircraft part so it could be cleaned up and resold.
I remember him showing me how to remove maintenance panels to reach parts that I had given up on or bolts I had missed. He showed me how sometimes you could only advance the ratchet one tiny click at a time…. but EVENTUALLY, that would be enough to get the job done.
What makes a ratchet handy is you can take a smaller range of motion and make use of forward progress in tightening or loosening.
In other words –
With a ratchet, you don't lose ground even when you change direction
This means you can keep working away at a problem even though half the time it seems like you are moving in the wrong direction, the ratchet only turns in the direction of progress even when you are turning it the opposite way and it DOESN'T LOSE GROUND.
You may have caught on but the ratchet is a metaphor for my grandpa's life and the lives and careers of most successful people. You make progress forward for a time in one direction and then face a setback… when your life is a ratchet you don't lose ground, you just get prepared for the next push forward.
The ratchet isn't the solution to a problem itself, it represents a way of looking at problems where you may not always gain ground but you aren't going to lose it so long as the ratchet is set to turn the right direction.
A handful of times my grandparents let me travel with them to pickup a wreck in another state. It was incredible pulling up to an aircraft with my grandparents and a few hours later having the wings off and everything loaded on a trailer… just the three of us.
All of it was done, one bolt at a time.
Ratchets in Society
This ratchet metaphor isn't something I made up, I've read and heard it multiple times from business and marketing author Seth Godin.
He speaks of ratchets in culture, technology, engineering – with each new “click” of the ratchet being a significant innovation or shift that changes everything moving forward.
Every new advance in battery technology or processor speed, or engineering modeling software creates a new “index” in the societal ratchet gears that act as a starting point for each new innovation.
In other words, many advances in society are cumulative, you can't go back to the “old way” even if you wanted to once efficiency and innovation have moved on.
This is an interesting concept, but I see ratchets as more applicable to you and my grandpa than to industry or society, at least when it comes to being useful.
The Ratchet Mindset
I was speaking with Jim Bergmann on the phone today about some of the new features and interfaces he's working on for MeasureQuick and though I've been planning to write this article for some time my conversation with him is what really got me to sit down and write it.
Jim's mind and the progress he's made on MeasureQuick is an example of a progress ratchet at work.
MeasureQuick is an accumulation of problem-solving knowledge over years and years of thinking and testing and calculation and recalculation and going back to the drawing board over and over again. In terms of a ratchet, Jim started in a really tight spot, without a lot of momentum where most people weren't asking for what he was making.
It reminds me of this quote attributed to Henry Ford (whether he actually said it or not, who knows).
Many times working a ratchet mindset is foreign to others who think like a wrench. In the minds of many to solve a problem you push in one direction and stopping to back up is a sign of failure. If you don't see the room to “swing the wrench” so to speak, many don't start something in the first place. The pain of failure and the anxiety of uncertainty often loom too large for someone with a wrench mindset so they end up getting stuck or working on a completely different bolt.
When I think of my successes and failures as well as men I look up to like Jim, my Grandpa, my Dad, and many others I can see the resilience of the ratchet in all of them.
They often face problems. Sometimes there isn't “room” to keep moving forward with the ratchet, but when you move back you lose no ground, you don't concede defeat, you don't allow progress to be lost even when you need to hit it from a new angle.
I hear from so many people who feel trapped in their job or career. Many of them ask me what to do next and sometimes I may have some advice. More often than not, that next step comes down to mindset and whether to think like a wrench or a ratchet.
A ratchet doesn't need much space, jusssst enough to make one little click and some time…. and some patience… and next thing you know that aircraft is in pieces.
In this LIVE episode we talk about diagnosing inverter systems and some of the issues and solutions for overvoltage
I was sitting in a session at the HVAC Excellence educators conference (which was excellent by the way) and my phone buzzed. So like a typical punk kid I looked down at it to see that my friend Josh had sent me a Facebook message asking if we served the East side of Orlando because he wanted an A/C maintenance on his home. I told him that we did not serve that part of town and I didn't think anything else about it.
Then yesterday I see this post
So we go out to look at it, and sure enough. The system is BARELY low, like 3 degrees of subcool low and we added 1/2 of a lb of R22 (weighed in) and did a leak detection. Yes, there was a TINY leak in the evaporator coil so Josh will probably end up getting a system at some point… However, the other tech did not do maintenance at all, he did not quote a coil or anything other than a system. He literally showed up, saw the unit was 14 years old, pulled out his leak detector, found a hit and wrote up a proposal for $5400.00. He tried to close the “deal” right on site. No load calculations, no looking at the ducts, just a leak detection, a proposal and run.
How many 14-year-old units have zero leaks?
He didn't clean the drain or the condenser coil, he hardly even checked the charge. Heck, Josh has a UV light that wasn't even working due to a simple loose connection, he didn't look at that.
Unfortunately for this company, my friend Josh is a local consumer advocate who goes on local TV news REGULARLY to talk about ways to save money and EXPOSE SCAMS.
When I contacted the owner of this business to try and reason with them they wrote me back that they were going to report me to the EPA because we recharged the unit. When I explained that recharging R22 on systems under 50 lbs is perfectly allowable they responded with more threats and emotional rantings.
The standard narrative is that there are just a bunch of greedy scammers out there trying to take advantage of people. Clearly this is true sometimes, but many times the story is longer and sadder than that, often this type of thing happens when well-meaning people get worn down.
Tell me if this sounds about right.
A new tech get's hired into the trade, maybe he has some schooling maybe he doesn't, either way, he get's his EPA license and starts riding around with another tech. The tech he rides with spends most of the day complaining about his boss, dispatch, other techs, customers and politics but almost no ACTUAL training. When they arrive at the job there are two main objectives
#1 – Get in and out as quickly as possible with as little work as possible.
#2 – Sell as much as possible during that short time. This can be hard start kits, capacitors and surge protectors some places, IAQ products others and some it's always finding a way to push a new system. For many, it's all three.
Usually, this makes the new tech feel at least a little uncomfortable but this starts to fade as the days of riding around whining broken by short stints of selling continue.
After a few months, the new tech is put into a van with some parts, pamphlets, invoices and proposal forms and set loose on the world. If he is smart, he realizes pretty quick that when his bosses talk about customer service what they really mean is making as much money as possible in a day with as few customer complaints and callbacks. Usually, the easiest way to do that is to condemn everything, when a system is replaced nobody ever knows if your diagnosis was correct or not. When you do a PM there is always something you can point to as a major issue that gives you an easy out, cleaning, after all, does not ring the register.
Techs justify their behavior
When I was still in trade school back in 1999 I participated in a skills challenge against other students from schools across Florida. There was another guy who was already working in the field and I remember him saying “I never just change one part, I change as many as I can and the customers never know the difference and their unit will last longer”. I was appalled then as I am now by this type of thinking but I'm pretty sure he honestly believed he was doing the right thing. He had been brainwashed into thinking that this was what being a technician meant.
So this all begs a question, who is to blame and what can be done about it?
The Root Cause
It is just easier to make money when you focus on selling instead of technical excellence. You can be great at what you do and still not make a profit but when you FOCUS on profit at every level you will usually make more of it…. for a while.
I actually blame the quality techs and companies who don't charge enough for what they do as one reason this happens.
I have been one of these contractors for years. We squeaked out a meager profit every year driving used vans, using cheap tools, trying to make ends meet and praying the vans don't break down. All the while, the sales-focused businesses have new trucks and spiffy, clean uniforms.
The good guys need to stand up and stop apologizing for what we charge and what we do. we need to CHARGE for the high-quality maintenance we do so that we actually make a profit on it. We need to diagnose the whole system and make quality recommendations to our customers based on the solid and complete diagnosis we perform. There is no reason we shouldn't be able to afford quality tools and a well-stocked van if we are the ones WHO ACTUALLY KNOW HOW TO USE THEM.
Instead, we beat one another up on price and undercut one another, calling another good, quality company who charges more a “rip off” or a “scam” just because they have their pricing figured out to where they can actually make a profit.
This company who went out my friend Josh's house was going to charge $5,400.00 for a 3.5 ton 14 SEER Heat Pump system, that isn't a crazy price but to some, it may be seen as a “ripoff” because they would charge $4,500.00. We might charge $6,000.00 for the same system… with a new return liner, and line set, installed with nitrogen flowing, evacuated to 300 microns, with a proper load calculation, permits and a perfectly weighed in charge confirmed by manufacturers specs to a proper subcool.
The “Ripoff” is the one who doesn't deliver on their promise, not the one who charges more.
What to do about it
If you are a manager or owner of a company make sure you are supporting your techs to get more TECHNICALLY sound and support them to use those legitimate technical skills to translate into profitable repairs and quality workmanship. Communication skills are key in a residential tech, a tech who understands IAQ like the back of his hand will naturally sell more IAQ products, a tech who understands airflow and duct design will sell more duct upgrades and the tech who understands complete system performance will make more needed repairs. This is a long road and there are no shortcuts.
R22 isn't illegal, not every customer needs a UV light, a hard start kit doesn't magically extend the life of all compressors, every PM isn't an opportunity to sell something and every system out of warranty doesn't NEED to be replaced.
If you are one of the good guys let's band together, keep our heads up and charge enough to have a good life.
Jim is back taking about common faults with high efficiency 90+ Condensing Ga furnaces and their installation
This article is written by RSES CM and excellent market refrigeration tech – Jeremy Smith
I frequently see techs online struggling with charging or troubleshooting refrigeration equipment and using subcooling as a diagnostic or charging method. Please don't do this unless you understand it fully.
Many times, trying to charge a refrigeration system to a specific subcooling value is going to result in a serious overcharge.
Glad you asked.. First, let’s take a look at a simple system and focus on the condenser, liquid line and metering device.
As we condense the refrigerant and fill the liquid line and condenser, the metering device restricts flow somewhat, causing liquid to back up into the condenser.
This ‘stacking’ effect as it’s commonly called, allows more time for the liquid to be in the condenser and to reject heat. That heat rejection is what results in additional subcooling. Adding more gas to this system will simply result in more liquid being stored in the condenser, more heat rejection from that liquid and, consequently an increasing subcooling value. That’s the system that you understand and that subcooling can be effectively used as a diagnostic and charging metric.
Now, let’s put a receiver in the system between the condenser and the metering device.
We’ve got liquid in the condenser and it enters the receiver before the metering device. As the liquid line fills and the metering device starts to restrict as before, where does the liquid wind up? The receiver. It doesn’t wind up in the condenser where heat can be rejected, but rather in a tank to be stored. Now, if you’re measuring subcooling, before OR AFTER the receiver, you’re not going to see a significant change in that value before or after we reach a proper charge.
If you continue to add gas to the system it’s going to continue to fill the receiver until that liquid backs up to the inlet port of the receiver. Now, you’re seriously overcharged because a receiver shouldn’t be more than 80% full, but the system can now back liquid up into the condenser and allow for the subcooling to increase.
This is why, when you have a receiver, you need to use either a sight glass or some form of receiver level monitoring to determine if you’re charge is correct and not just use subcooling.
— Jeremy Smith