The point that I was trying to make was you not only have to be able to troubleshoot electrically, knowing who controls what is just as important.
You walk up and compressor isn't running. Start checking your safety circuit and LPS is open. We all know where to go from there. Question is, if you didn't know that your next stop should be the tsat or the llsv, what benefit would more electrical theory/practical experience would help you?
Yes, sequence of operation plays as equal a roll in the troubleshooting process. At least it sure does speed things up. If one starts at the end and then ends up at the beginning only to fine that the power is off. That sure is a waste of time. ;)
I never accurately tracked, but I'd say electrical issues (including motors) are 50% or greater of the issues I see. In fact, hooking up my refrigeration gauges is the last thing I do. I'll use my Fluke 52 or my Fluke 116 much sooner.
Troubleshooting is troubleshooting. It doesn't matter what percentage of problems are electrical, mechanical, refrigeration, or dirt. You better be compatent in all phases. All are equally important because every call is different. If its an electrical problem being an ace mechanical tech doesn't help. If its a ref problem an electrician will be screwed. Etc etc etc.
I was recently in your position, but i got lucky and was able to learn by experience with my company we got a ton of refer accounts all at once. From my experience i found reading in your hvac book from school helpes a little bit well to get to know the sequence of operations of each different application, and talk to pple from this website helped me out alot!
I would have to agree with Ryan and capz as well. Sequence of operations and elec knowledge is crucial. How are you supposed to troubleshoot something if you don't know what it's supposed to be doing? I'm a CSR for Manitowoc and in my opinion you might as well memorize the sequence of operations before you even break out the 6 n 1. Also, you MUST be knowledgeable in different Freons and their pressures. Most all refrigeration equipment is critically charged, especially ice machines. Good luck my friend, and be prepared to never go out to eat again. You will see.
I know what you mean!
Originally Posted by SeanH
When I cleaned my first ice machine, I became fearful of placing any commercially produced ice in my mouth, LOL!!!
I don't even want to eat in any restaurant where the lowest price item is less than $20!!!!!
Let me make a list for the OP:
1) Learn all about electricity. Electronics is a great way to begin, as you can buy one of those "200 electrical experiment lab" gadgets at the electronics parts store (you know, the one that sells cell phones now?) or you can search online and find a GREAT deal. Nothing will make a wiring diagram on a walk-in look simpler than being able to understand a Darlington transistor setup.
2) Everything has a sequence of operation. Find out what makes things work.
3) Learn about how refrigeration compressors operate. A typical reach-in will have a small hermetic compressor with some sort of starting and overload components. Learn the difference between a current relay setup and a potential relay setup, and how they are wired to an overload and the three compressor terminals.
4) Dick Wirz has an excellent book on transitioning from HVAC to refrigeration.
5) Perhaps the most important change in thinking is to start looking at temperatures instead of pressures. When you work only with comfort cooling, especially commercial where many rooftops are still a decade away from being replaced by a 410A unit, you get used to looking at the gauges and thinking about pressures. Then, when you look at a different refrigerant system, you are lost. Temps will always be similar in a similar application, such as comfort cooling, medium temp boxes, low temp boxes, etc.
Refrigeration is far more challenging, because it is more unforgiving, forcing you to raise your game. A HO may be satisfied if their house is cool, but food that is not cold or frozen will make your phone ring.
All good points here. You can thank the health departments for your last sentence. :grin2:
Originally Posted by timebuilder
...or the folks who send their food back because it is a little "off." :(
Originally Posted by VTP99
Was it the Chicken or the Egg first?
Unless you understand how a machine is supposed to work from the factory or as it was designed in the field, troubleshooting is kind of impossible.
After 30 years, I would offer that probably 90% of the workers in HVACR have no idea how the systems they work on actually work exactly.
This is the reason we have a world of parts changers instead of true troubleshooters, and also the reason probably 90% of systems end up being replaced or wounded beyond recovery unnecessarily. A bad run capacitor is a bad compressor, a bad TXV is met with an extra 4 pounds of refrigerant, and lots of call backs are created, etc...
All that being said understand that if you don't understand how system are supposed to work, it will be very hard to figure out if the system as it stands ever really worked properly.
Many years ago as an idealistic young technician I did not understand that some folks have no clue what they are doing, just figured if you were working in the business you had to know what you were doing. This was until I ran into my almost Waterloo call; the refrigerated case worked to the customers satisfaction most of the time (so he said). The intermittent problem was indirectly witnessed via a chart recorder I installed in the case.
To make a long painful (profit wise) story short I finally discovered the compressor had been changed out with one from an air conditioning unit. The refrigerated case a R-12 unit, had a used 5 ton R-22 compressor installed. I later found out this was done by the store owners nephew who was in tech school.
This fellow had also installed a few condenser fan motors to run backwards, as well as replacing a 3 ton Lennox heat pump with 4 ton Janitrol cooling only unit. He was confused by the HP18-411 name plate.
I also came to the understanding that sometimes it is better to take a day off then to work for transplants from Europe or Asia if you want to make a living.
I have one rule that I have managed to pass along:
unless you speak the same language as a FIRST language as the customer, and you share a cultural norm, it is a bad idea to try and deal with them on a business basis. Leave them to the local practitioner who has bonded with them and understands their way of doing business.
A lack of understanding can breed fear and contempt; the customer thinks you are out to rip him off. It is VERY difficult to bridge that gap with explanations of needed repairs, or level of responsibility for the function of an entire system, once a simple, inexpensive repair has been made in the past.
Some folks grew up in a "bazaar" or "bargaining" culture. They feel it is their moral duty to bring you down on price. They don't recognize the American idea that I tell you what the price is, and then, you PAY that price.
Sounds like someone has had to arm wrestle some foreigners.:whistle: I guess I have a little advantage in that arena ( having traveled overseas ) I had to adapt to survive in those cultures. The basic code was " when in Rome act like the Romans ". Problem here is they seem to not follow that same practice. More and more of my customers are becoming foreigners. I have had to developed new ways to tend with this. One thing I have found to be true is once you have there trust the haggling seems to go away.
Maybe I should have not left that statement just hanging at the end.
Originally Posted by VTP99
Not all from the other side of the ocean are impossible to deal with, and yes I learned how to play the game. At one time in my refrigeration carrier I had just about every Chinese restaurant in the China town section of Philadelphia as a customer I also had quite a few of the big players in the Greek community. I even had one of the largest Palestinian owned supermarket chains as a customer. We were 50-50 hvac and refrigeration.
One day I decided I was tired of grease, cockroaches, mice and rat crap, and the emergencies involved in refrigeration. Most of all the 20 minute repair and the 15 minutes of crying "Oh!, do you know how many breakfast specials I have to sell to make this up?" No and I really couldn't give a crap Gus.
I decided to go 100% hvac, bought a sheet metal shop and marketed for the jobs that most in my area cannot do, and the those that did, were mediocre at best.
We also took up hydronic heat, now days we mostly propose replacing traditional hot air with hydro air which allows most of the ducting to go away, allows the mechanical room to move away from the chimney, and replaces the traditional tanked hot water heater. Customers love the idea of tankless, which in some cases includes removing the DWH as well.
The customers who call us today are looking for a solution, most have been beat up by other contractors or have purchased dysfunctional new construction.
That is nice because they are not holding a coupon or looking for a deal, I discount installations by removing items, want $200 off no problem you get a T87F.
Btw, I have also traveled a bit out of the USA, I corrected your quote to better describe what to look out for when overseas.