There's always been a difference between the professional automotive technician and the weekend mechanic. These days the gap is growing ever wider with the technology changes. However, a lot of DIY'rs still are doing repairs at home and believe they know more than the professional tech even after admitting they don't know what they aredoing. Not to say there isn't adifference between the levels of knowledge at the corner repair shop and the next shop down the street. Sure, always has been. But, that's a result of experience, education and what type of repair is common to that certain repair facility... nobody knows it all. But, imagine how much difference there is between the uneducated, unfamiliar, and down right dumber than dumb person who tries to repair their car at home.
I get a lot of these "home" repair guys in the shop with their family cars whose first claim to fame is how much money they are saving by doing the work themselves. Yes, professional auto care can be expensive, and in a lot instances you can save a few bucks by doing the physical labor yourself. On the other hand, there's an assumption made that you know what you're doing. This is where a lot of socket jockeys get themselves into trouble. Now with small hand held scanners and meters out in the market place there's an even bigger chance of a complete disaster waiting to happen.
Take a problem I was involved with just a few weeks ago. A DIY'rs daughter's air conditioning wasn't working on a 99 Ford Escort. From his meager test results he saw a 12 volt reading at the clutch. His gut reaction was the clutch must be bad, which means a trip down to the local cheap-o-depot for a replacement compressor. After spewing the refrigerant into the atmosphere and more than likely a good amount of the oil he did managed to get the compressor replaced. Then he added a new can of refrigerant to the system. To put the second can in he had to start the car. Oh, oh...problem...the compressor still doesn't come on.
"I checked it again and I still had 12 volts so I don't know what's wrong with it now. That's the only reason I'm bringing it to you," the DIY'r tells me.
Knowing that most of these guys really don't want to spend a dime on repairs, especially something they feel they can do themselves I figured I would save him diagnostic time by helping him out a bit. I told him, "If you have 12 volts at the compressor sir, then it's most likely a bad coil on the compressor."
"Nope, can't be..., it's new"
I've lost count how many times somebody has told me the new part can't be the problem... because it's new. So I not only doubt the quality of his part but his test results as well.
"Well, then...there's only one of two things it can be. Either it's a bad coil on the compressor or... you really don't have 12 volts at the coil," I told him.
He still insisted he was right and that I needed to check it out further.
Once I had it in the service bay I checked the voltage at the coil. Hmmm, that's peculiar... no voltage. This car uses a unit called a CCRM (Constant Control Relay Module) this module has several purposes but the one I'm concerned with is the 12 volts for the compressor clutch. I checked the output lead that lead from the CCRM to the coil... nothing. I then checked the signal from the PCM that controls the activation signal to the internal relay for the compressor at theCCRM. Perfect, no problem there. The culprit in this case turns out to be a faulty CCRM. Not a big deal, I'll call him and let him know.
I gave him the option of doing the job himself, but he wanted me to do it since it was an "electrical" problem. All-righty then, I can do that, and while I'm at it I'll make sure he has the correct amount of refrigerant too. Everything seemed fine until he came to pickup the car. That's when this CrackerJack qualified DIY'r sticks his chest out and tells me his version of how to diagnose it and fix it. As usual, the wife is standing next to him for encouragement.
"I had 12 volts at the coil so why didn't it work?"
"Actually, there was no voltage at the coil."
"Are you telling me I don't know how to read a volt meter?"
"I'm saying you probably misread the meter, that's all."
"I've been fixing cars for years.You're not going to tell me I don't know what I'm doing. You did something else to the car! You electrical guys have a trick to making things work and then I've got to pay for it!"
"No, I'm afraid not. I replaced the CCRM and recharged the system with the proper amount of refrigerant."
"I can put the refrigerant in."
"How much did you plan on adding?"
"I keep adding more until it's cold."
"That's not a good practice sir; you should put in the amount it's supposed to have."
"I guess you assume I don't know whatI'm doing at all... do ya?"
You can imagine the rest of the conversation. I've stood at the service counter for many years and have been on the receiving end of these DIY'rs retributions before. Nothing new, might as well take their abusive comments, straighten the desk a little, jot a few notes down and wait for them to finish. (Never interrupt them... it will only take longer.) In his mind and explanation, (as usual) I turn out to be not only acomplete idiot, but have no reason for being in business. Obviously as he stated, I've been at this car stuff for nearly 30 years and have been doing it entirely wrong all this time. (Glad I found out now... geez...another couple of years of doing it wrong would have been devastating.) You know, after spending time in classes, schools, conventions and on the job perfecting my trade, I find that listening to these wanna-be mechanics blare out their reasons for owning a tool box only amounts to a whole lot hot air.
Well, one thing is for sure... he left the shop with cold air in his car. Maybe he needs to drive around for a while and cool off. Then go home, take a class or something in the proper use of a multimeter. I don't like to assume I know, because all it does is make an ass out of U and me. There are plenty of tech schools and on line classes out there that will teach you how to be a mechanic.
The old saying says it best; Stupid's free...but you pay for knowledge... the pros know it already... the novice just assumes it.