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Norm
You ought to write a trouble shooters book called "Isolate & Verify." You can use the name as long as I get some credit somewhere. Just one little line maybe way below your name or in the back of the book. I am trying to be as famous as Diceman.

Seriousness aside, I founded that term years ago when all these non-HVAC computer geeks starting getting into our business and messing things up.

I found that with their controls and stuff I have needed to isolate any of their stuff away from the "real HVAC" stuff in order to do any worthwhile trouble shooting.

There exists two levels of techniques for trouble shooting since and because of the days on the electronic invasion. The mechanical parts still get the same look ats' from way back since the compressor was invented. And their mechanical demise is typically progressive, logical, symptomatic and in a downward spiral.

On the other hand, with electronics absolutely any type of non-locigal, non-progressive, intermintent, off-the-wall problem is possible. I just am now attempting to work on a large local college where the DDC guys installed and programmed the 8 HVAC units. As I am working on one, the two other are cycling on and off, on and off, on and off at different very short intervals as programmed by the DDC guy. Talk about a compressor killer. I told him about it but he doesn't understand, period.

I call it the Bill Gates syndrom. You get to make a lot of money from inventing things that are undependable for which you get to invent other things and make more money from the same customers selling them the add-on or corrective stuff which might make the original stuff dependable.

1. Ears first listen to the customer
2 thermometer and meter
3. gauges
take care all

Originally posted by DeltaT
To me, good trouble shooters do two things. Isolate and verify. Cause there's a whole bunch of stuff under that, like knowing what a part does first and how the refrigeration cycle, electricity, etc. works.

But it always come down to isolate and verify.

I am particularly drawn to this one by Delta T. Simple, to the point and accurate.

Isolate and verify

then after making the correction; check for the possibility of yet another problem.

Sometimes there is an inner sence, a sixth sence of what might be left undiscovered.

Ignoring this gift will result in a possible call back if left unchecked.
We must not get ourselves in a rush to leave the site or we'll be back soon for sure.
AN extra fifteen minutes to walk again thru the job will be billable to the customer. And it looks like we are being thurough. Which we are.
If we neglect this vital step in our checklist, we might be back. But next time it will be on our own time, for free!

Since we are created so complex, we are able to have a sence of something being amiss even though at the first, we may fail to recognise what it is.


You get to the job and first thing you find is poor airflow. Yo begin opening up sheetmetal and discover a fan blade which is bad.
Next thing you know, your back in the van heading down the road for a part.
When you arrive back at the job, your mind is already closing out the paperwork. Your looking at your watch, maybe phoning dispatch with your eta of departure, mentally going over what you have to do to leave here.

........ all the while, you have not found all of the problem! Only part of it.
And your mind is set on leaving. And it's very very hard to wrestle that focus away from your mind while you are yet on site.

Once you find something obvious, step back and try to fit it in to the big picture.
Ask how this fan blade affects overall performance.

Is this fan blade "one of many" which are broken?
Is this fan blade crucial to the system?
Could there be anything else, could there be ANYTHING ELSE which is more significant than this fan blade?

If we are disciplined enough to ask these questions BEFORE we go running off to the supply house, then we are most likely to NOT have a call back and we are also more likely than not to be able to find THE problem rather than just some bad maintenance.


The examples I was thinking of here were quite embarassing, so I will spare y'all the details.



[Edited by R12rules on 07-22-2004 at 07:11 PM]

A good tech can identify everything that is right, whatever is left must be the problem.

By this I mean, to many times a tech can only identify the end result...not the problem that created it.

Look at everything, not just what appears to be broken.

I was taught to do the T.E.C.H. METHOD

I still do it on every call I do.

T=Thermostat
Check to see if the thermostat is set properly, check the wiring and make sure all is connected/tight. Is it level and secure against wall. When in cool/heat does the unit come on, does it come on when turning fan on? Is the thermostat reading the correct temperature or does it need to be calibrated?

E=Evaporator
Check everything out in the air handler. Is the unit coming on, is there any loose or crushed duct work, is the coil clear and clean? Is the blower clean and turning properly, is the filter clean, does the unit seem to be draining properly? What's the air flow like?

C=Condenser
What are the coils like, does the motor come on, compressor, what the pressures, superheat, subcool? What is my amp reading. What is the size of the unit compared to the size of the house, properly matched? Is there bushes around unit needing trimmed, what about armaflex and wiring? How the electrical look. What's the airflow like?

H=Heating
Are the heaters coming on in cool mode, if heat pump is it cycling in heat mode or is emer. heat coming on?


When I find the propblem, I still go through all the motions of the TECH method. It is amazing how many times you'll find other problems after the system seems to be running correctly. I also almost always recheck the unit before leaving. I let it run in cooling first and then heat to make sure both are working.

One of the biggest things I have learned is that start simple and work up to complex. It usually is something as stupid as a dirty filter or loose wire.

I mean, I do look good in a skirt and all......but...

There are several good points in these posts and the ones I always personally apply are: "Never assume anything" and "Isolate and test seperately". There is also the notion of logically breaking down a system or device to its simplest, generic function and having an intimate knowledge of how it works; independant of brand or features. I've learned and worked in electronics and there are certain approaches that have never failed me, even on equipment that was unfamiliar to me. Things like checking the power supply: no matter how good a piece of equipment may be, if the power getting to it is bad you will see all kinds of strange symptoms because it is not being fed properly. Then there is the other end, check the load: for HVAC systems this can be things like airflow, duct obstructions, blower not spinning freely, dirty coil, etc. Only once you have determined that the power source and the load are ok can you be sure that there is something wrong with the equipment itself.

Originally posted by hvacbear
Don't take anyones word on what they "checked for sure" if you are asked to look at another persons problem.

Here is why I don't look at previous service tickets until I need to. I check everything myself in my own sequence.

1) Airflow
2) Everything else

Don't take anyones word on what they "checked for sure" if you are asked to look at another persons problem.

Originally posted by NormChris


I cast my vote for Dice as secretary. He could comple them, put his name on it and submit to to Don for posting in the "For Your Interest" section.

What do you say, Dice?

[/B]

Does this mean I have to wear a ahort skirt and sit on your lap??
Anyway, I wouldn't want to act like I made em all up myself.

"5) When you get stumped, back down. Hardest thing to do in a time crunch but the time spent on a break is time saved when you return to the job and nail it. "

That one from shophound works good too when I get into an analysis paralysis mode its amazing how the answer can come when I stop thinking at least slow those wheels upstairs a little bit down take a little break remove myself from the situation for few or grab a bite to eat or something then come back and the solution just comes and I start feeling like an idiot because it's usually something much less complex then I the theories I had spinning in my mind.

Makes me wonder maybe there is a market for shrinks geared to techs?

Residential a/c isn't bad but when you have walkin cooler down with thousands of dollars of meat in it a restaurant GM up your butt wanting to know exactly what the problem is, when exactly it will be fixed, and what exactly it is going to cost and u haven't even pulled your tools off the van yet it can be a bit stressful. Then watch the Gm's face when you tell him u need to step back take a break and let the answer come to you!

I try to wash my brain before each call. Then as other said isolate and verify and I always start with the basics thats why I try to wash my brain first becuase if I think about it why its not working before I get there my cristal ball comes up with all kinds of scenarios before I even ring the doorbell. I have the unit with a bad txv or reversing valve a freon leak, or something and it turns out I pull out a dirty filter clean it and everything tests fine. Guess I am always hoping my job is a little more glamorous then just changing a filter so I try not to predict whats wrong anymore. I now leave the "rush to judgement" solely to the Cops.

-You should know what the equipment should do.
-Observe what the equipment is doing

To me, good trouble shooters do two things. Isolate and verify. Cause there's a whole bunch of stuff under that, like knowing what a part does first and how the refrigeration cycle, electricity, etc. works.

But it always come down to isolate and verify.

I agree with R-12 Keep it simple stupid. Start at the beginning (power) and keep going until you find your problem.

On every job you should record Suction pressure, liquid pressure, superheat, sub cooling, condenser split, evaporator split, voltage drop across all contactors, and relays, running, and non running voltage, and amperage.

If you diagnosing a running unit, after you find what you think is the problem, take your splits again this will tell you if you really fixed it.

If your stumped talk to someone else, another viewpoint can be enlightening. Like they say, the only stupid question is the one you don't ask.

When you are stumped start over(after a break) you usually overlooked something simple breaker fuse ect.

Re: Laying of the Hands

Originally posted by actnowhvac
Good God Almighty!!!!!!
I like being a faith healer for 5 minutes

Just don't forget to pass the collection plate when you have performed the miracle!

Good to see you back, Actnow.

Originally posted by Boss
When you guys think this thread has gathered all the tips you want, and leaving it open any longer will just let it wander off topic, just let me know and I can just move it to the FYI section.

I've done it again....
I'm doomed

Laying of the Hands

Good God Almighty!!!!!!
I lay the hands over the condensers.....
*No air...... Start at the wall ( Electrical, indoor unit off, etc. )
*No heat a rising!!!.... Start at the System ( Indoor unit, Charge, etc )
Go indoors:::
Then I lay the hands on the supply!!!!! Oh demon get out !!!
*No air flow ( filter, fan, etc )
*No cold air ..( back to the system charge etc.. )
Shasammmm.....75% of problems elinimated.
I then place my hands over the customer and cast out the demon.
Otherwise....
I get the tools out and become an ordinary tech,
systematically eliminating the obvious. Working diligently
through each aspect of the system.

But I like being a faith healer for 5 minutes