You may have heard some variation of You can't learn anything if you already know everything. Well, I had an amusing, slightly embarrassing thing happen to me that illustrated this point.
Back in mid-May, I noticed that my car wasn't cooling down very much when I was using the air conditioner; it was blowing slightly warm air. This was odd, given that I'd purchased the new car a year-and-a-half ago, and you wouldn't think that the air conditioner would have problems already. I thought to myself that it was probably just low on Freon. I was due to bring the car in for an oil change anyway, so I'd have them look at the air conditioner then.
So, I bring in the car for an unscheduled visit to my dealer's Service Department, and I told them about the air conditioning problem. They say that they can do the oil change, but that the air conditioner situation often requires that they run more diagnostics; I'd have to make an appointment for another day to get that checked.
Feeling a bit disgruntled, I put it off for another few weeks. That being said, Baltimore summers are hot and humid, and it wasn't long before the heat drove me to make another appointment. Dropping the car off, the attendant looked concerned when I said I'd wait in the lounge until they were done. He told me that air conditioning situations could run hours. I sighed, raised my eyebrows, and told him that I'd still like to wait for it.
Settling into the lounge, I set up my laptop, plugged it in, got some caffeine, and began to do some work. After only 10 minutes or so, the smiling attendant approached, and asked me to step outside with him; he wanted to show me something.
In a very cheerful, professional tone, the attendant began to explain to me how that red-and-blue hotter/colder dial on the dashboard worked. Within seconds it occurred to me what I'd done. The air conditioner worked fine. I'd been driving around for a month with the heat partially turned on. DOH!
Before all these "air conditioning problems" began, we had an unseasonably cool late-Spring day, and I'd turned the heat on a little bit, just enough to put out slightly warm air. After a few weeks, when I needed the air conditioner, I turned it on, and it blew lukewarm. Given that I knew...I KNEW...what the problem was, there was no need to check the temperature dial. It didn't even OCCUR to me to do so.
I began to chortle loudly at what I'd done. The attendant tried to "make me feel better about it" (what do you want to bet he'd seen this before), but I assured him that it was OK to laugh at my foolishness. Oy!
So, in general, life often goes smoother if we're a little less certain about things. :-)