Don't Touch that Dial

[Dan]

God was kind to me. My worst refrigeration stupid thing I did was to tighten a flare nut without having any other tools to valve off compressors and the other necessary tools needed to stop the enormously loud and magnificent loss of refrigerant, as I stood by waiting for my backup.

Watching the fog
Hearing the loud hiss
Wishing the world would just swallow me whole.

But this thread is not about screwing up by touching things: This thread is about why not to touch things.

Dan

[subzero*psia]

Okay, Okay... I know you all think I am perfect but... LOL!!! I was working in the restaurant section of a bar/pub full of people... some that I knew.

I had ordered a condensing unit to slip into an undercounter cooler prep table. Well heck, everything was zipping along pretty good. I had plenty of line set because it was coiled so you could slide the condensing unit out for service etc. I had the unit out front, made my sweats etc. and went to slide the dang thing in.

This is where the embarassing part comes in. The base plate is all of one quarter inch too wide. So I get my die grinder out and try grinding the side frames... slow and sparks are flying at least 6 feet away! So I figure maybe I can grind the corners of the base and roll one edge all the way down... loud, metallic beating from the framing hammer I am now using to roll the edge... definitely looking professional now. I finally get it to fit, all but the last two to three inches of it... but hey, I can make that slide in there... I mean come on, the human legs have very powerful muscles in them. I got the unit in and it ran like a charm, but I will never forget the looks some people gave me. I felt real tiny.... but dang if I was going to pull that c.u. and recover the refrigerant again!

Next day I called the manufacturer, they told me they had a batch of c.u. base plates that had been formed wrong and were slightly wider than normal. DUH!

I hate to think of what those folks probably said while I was there and then again after I left!

[Dan]

You made my Saturday smile with that one, Dean.

Dan

[Gary]

I'm not sure where we are going with this thread, Dan. When I think of things the service technician should not touch, what immediately comes to mind is TXV superheat adjustment.

This isn't always true, but it is almost always true.

What it comes down to is knowing when to touch what. In other words, trouble shooting skills.

I see the problem right here in these threads. Someone vaguely describes a system malfunction, and everyone guesses what might be the cause. That's not trouble shooting. That's guessing. Why? Because that's all anyone CAN do when presented with insufficient symptoms (lack of clues).

I am amazed and appalled at the number of service technicians who try to trouble shoot systems while considering only a few of the symptoms. You might say they are clueless.

[Edited by Gary on 11-06-2001 at 12:44 PM]

[Gary]

And then there are calibrated fingertips.

The average human hand is incapable of differentiating less than 10*F. In other words, if you stuck your hands in two tubs of water, you couldn't tell which was warmer and which was colder unless there was at least 10*F difference.

But then, that's average. We in this trade have calibrated fingertips, right?

What can we tell with our calibrated fingertips? We can tell extremes.

We can wrap our fingers around the pipes and say, "Too hot" or "Too cold", make the easy call, solve the obvious problem, and impress people who couldn't find a problem if it bit them in the butt.

But some problems are a little more difficult. And that's why God made thermometers.

[subzero*psia]

Chill out Gary.... "the guess work" is supposed to help point the tech in a general direction not tell him what is wrong. I haven't seen anybody give a descent set of measurements (ie: suction/head pressure, evaporator superheat, compressor superheat, measured ambient, running load amps, subcooling.... need I go on?) That is for the tech, he should gather that while he is there and make an actual diagnosis. This is a fun board... and we help each other while having fun.

I changed the system on a walkin beer cooler at a clubhouse Friday night, finished Saturday morning, c.u. and evaporator fan coil assembly... the whole shabang. I removed the old system which was a through the wall system or in other words there was a 16" x 21" hole in the side that had to be finished off. The system I chose wasn't anything big.... 7000 btuh, R-22, 1 ton ext. equalized TXV. Time came to start the system. The valve was hunting, 15 psig swing. The club had at least 30 cases of beer that had warmed to about 55 or 60 degrees F. As the beer dropped... so did the swing in the hunt. Now perhaps a tech would have wanted to "touch" that superheat spring eh? Even experienced techs won't wait for 3 hours usually will they? Don't touch that dial!

[Gary]

That's a great example, Dean. A lot of techs would have both cleared the sightglass and adjusted the superheat.

Got it out of my system. I'll go take a nap now.

Chillin'

[Gary]

hmmmm...embarrassing moments.

I was working on one of the many A/C units in a stadium sized computer room (Ford World Headquarters). Went to the power panel, threw the wrong switch, and the entire room went silent. Said "oops" and threw the switch back on. Turned around and all eyes were upon me.

Was informed the next day that I dumped $35,000 worth of programming in that brief moment.


[Edited by Gary on 11-06-2001 at 01:40 PM]

[Dan]

I cannot argue with the failures of touchy feely troubleshooting, but I still admire the mechanic who puts his hand on the tailpipe after he has the computers hooked up.

The trick, and perhaps the sense of this thread is to not permit information gathering to dictate making adjustments to things.

"Don't touch that dial" does not mean that you cannot use whatever methods available to get a feel for things. As a process, even flawed observations help to lead one to make better observations. I see it as a homing in process. Hunches come into play... prejudices enter... past experience actually DOES have practical duty in the discovery process, as it eliminates dead-end trails before they are embarked upon.

However,"Do no harm" comes quickly to mind, as a possible first rule of trouble shooting. "Don't touch that Dial."

Altering any adjustment on anything that has been working for any length of time is the last option we should choose even after collecting mounds of data that indicate we should do so. Our caibrated fingertips help us decide that we have a faulty transducer, every now and then.

Dan

[Gary]

Don't get me wrong, Dan. I use my calibrated fingertips a lot, but I view them for what they are; Ball park thermometers, guaranteed accurate plus or minus 10*F or so. Good for making the easy calls.

The first rule of trouble shooting is: Don't use your calibrated tongue for checking superheat.

[subzero*psia]

I can agree with that... fingertips are ballpark gages only. Hey Gary.... your story was toooo funny!!! LOL!!

[Steve]

That reminds me of an engineer that I know who licked the suction pipe of a satellite compressor and who was stuck there for a while.........

[bernie]

craziest thing ive ever done? Please dont show this to anyone.
It was hot july day, im running a service call up north(chicago).
I get a call from the shop telling me our installation guys are up on the roof, crane is there waiting to pick the unit for replacement.
They tell me they cant find the breaker to disconnect the wiring. So theyturn me around to go bail them out. I was annoyed to say the least. Upon arrival 3 more calls had come in to the shop and it was now 12 noon. I climbed the ladder, the guys said hello, I took out my trusty linemans pliers and shorted one leg to ground
and blew the breaker. All i said to them as I was leaving was " NOW GO SEE WHERE ITS DARK."

[Dan]

Interesting story for this thread, Bernie. If you think about it. You being in Chicago, I would have thought that the Electrical Locals would have have Short-to-ground-Gaffers that wouldn't permit you to do that without a proper Rigger.

In Florida, especially during remodels, shorting circuits to find the breaker is way too commonplace. But it is what happens at night. And it feeds down to the fridge guys when the electrician is not on site. And it feeds down to the carpenter if the fridge guy is not on site., who does the same. Can we agree that this is an unsafe practice?

Your fellows were perhaps properly shy about wondering where the breaker was. Then we have to put into the equation that 4 guys were standing around doing nothing and costing money, and you... a single person could reroute yourself, and have your picture taken with a spark and disappear from the scene with minor advice, and all of us just assuming that the breaker is not oversized for the wire or equipment, which is a leap of faith, when you think about it.

"Don't touch that dial" for me is we should be careful about what we are doing. More careful than what we really are. All we need to repeat to ourselves is that we should be slow to touch that dial. That we all know that it is not okay for us to break our rules and touch the dial.

I am guilty of doing all of this, either in person or with those who work for me by omission of caveats. Even on finer points within control circuit troubleshooting over the phone I advise a tech to just short the circuit when we are missing key evidence... when we are not really communicating. There mostly is a flash bulb. We call it getting your picture taken.

It works in a practical sense. It shortens billing hours most often. I will change my mind when I explode the main panel and set the building on fire, however. It is the dare we take everyday, as we compete, and compromise good practice.

There is a monetary element to what we do that defies perfection, expects performance, and demands profitability.

That's why, Bernie, shorting a circuit saved money for both the customer and your company. Good practice, bad practice, best practice? I don't think a good toubleshooting book can address such a decision in its entirety.

To me, anyway, touching a live wire to a neutral is sort of like "Touching the Dial."

Blind trust that there is upward protection in place. Shucks, as I think about it, most dialy things are electrical in nature.

I am going to be stubborn on this. Shorting out circuits is within the realm of touching dials.... and it is wrong. It is not something we should do.

I am not so sure that there is a significant difference between twisting a stem on an EPR, TEV, or CRO as compared to shorting circuits.

Dan

[bernie]

ok dan you win, i put my application in at walmart today.
I meant to title it the dumbest thing Ive ever done.
I promise ill never do it again.

[Dan]

LOL Bernie. I guess I ranted there. I have yet to meet a Walmart greeter that I didn't like, however.

After rereading my own post, it is apparent that I am uncomfortable that I break all of my own rules.

I wonder if it is because I am Catholic.

Dan

[Gary]

Getting back to the subject of the thread:

Consider all of the adjustable components in a system. Once properly adjusted, can anyone give me a good reason why any of these should ever be adjusted again?

[Prof Sporlan]

Educating oneself on what happens when valve adjustments get all screwed up?

[Brian_UK]

Originally posted by Gary
Once properly adjusted, can anyone give me a good reason why any of these should ever be adjusted again?

1. Mechanical moving things wear causing maladjustment.

2. Electrical/electronic systems can suffer degradation of components, resistor changing resistance etc., causing calibration to change.

3. But, on the whole, if it ain't broke - don't fix it

[subzero*psia]

Originally posted by Prof Sporlan
Educating oneself on what happens when valve adjustments get all screwed up?

NOW THAT IS TOO FUNNY!!!


And probably the best answer to Gary's question too!!

[Gary]

Educating oneself on what happens when valve adjustments get all screwed up?

Good answer...lol

Worn components are in need of replacement, not adjustment.

I've heard that resistors can degrade, but I've seen no evidence of this. Most calibrations I've done have been following someone who tinkered with the controls.

[Derek]

So I walk into a local petrol station last summer and the kids go to grab a coke from the cabinet. Scream Dad its hot. Sure enough the cabinet is showing 55C. Advise assistant to pull the plug as fluid under temperature of 55C a) wont sell b) may just rupture the containers.

Reply...We called the engineer and he said touch nothing so we won't touch nothing not even the plug. Cause.. well methinks some enterprising type had reset the controller. Makes you wonder why it was selected with such a max.

Does your coke taste funny?

[Gary]

Cause.. well methinks some enterprising type had reset the controller.

Hmmmm...the cause could have been just about anything, the most likely being dirty condenser.

[leonardbtessier]

clean it,juice it,adjust it,forget about it.