Get any group of service technicians together, and we love to tell war stories of the mistakes we have made throughout the years. It's great to hear these stories for two reasons: 1) We learn what not to do from others, and 2) It's nice to know others have made some of the same mistakes we have made.

Here are some of the mistakes — not all — that I have made over the 38 years I've been in this industry:

1. Once I was changing out an R-134a compressor, and I charged it with R-22. I was in a rush, and it was not well lit in my truck or on the jobsite, and the shades of light blue and light green kind of look alike. I did realize my mistake relatively quickly when the pressures were not quite right. I learned to always be cautious when adding refrigerant to a system — especially today, when we might be using a refrigerant cylinder that is not color-coded.
2. On one service call, I did not check the service valve or Schrader valve after I removed my gauges, and I left a valve leaking on a system, causing it to lose all its refrigerant. The next day I was out again and had to recharge the system and tighten the core on the Schrader valve — definitely a costly mistake for me. These days, I always check if the service valve or Schrader valve I attached my gauges to is leaking before I leave the job.
3. When I first started out in the trade back in the 1980s, I worked for my dad’s refrigeration shop. At the time, we serviced some household refrigerators, and a common issue was an iced-over evaporator caused by a defective defrost timer. A relatively simple problem to diagnose and repair — defrost the evaporator, change out the defrost timer, and you're done. Well, one day I was in a rush to defrost the evaporator, so I chiseled away the ice and chiseled right into the evaporator. A simple problem ended up costing the customer a new refrigerator. Not a good day.
4. Again, when I worked for my dad, we serviced and installed window air conditioners. I was installing a window conditioner on the 10^th floor of a high-rise apartment building in New York City. It was a slide-out air conditioner, so you would mount the case first and then slide in the air conditioner. The case I was installing was just a little too big for the window, maybe ½-inch too big. I was determined to make it fit, so I started banging on the case. Well, I hit it too hard too many times, and the case buckled and flew right out the window and landed 10 stories down in the courtyard. Luckily no one was in the courtyard at the time, but my dad and my fellow workers never let me live that one down.
5. When I was installing an outdoor condensing unit, there was no good place to mount the disconnect. I decided to mount it on the condensing unit, and I drilled right into the condenser coil. Not a good day for sure. I learned to always be careful when drilling around any equipment, because it is an easy mistake to make and is actually quite commonly made by technicians.
6. I was installing a commercial ice machine in a customer's home, and it was a beautiful home. The drain went to a floor drain behind the machine, and I did not quite line it up properly. When the machine went into harvest and purged the water from the trough a good bit of water went on the floor. Since it was behind the machine, I did not notice the issue until someone came up from the basement under us and said water was coming down from the ceiling. That mistake cost us $1,000 for new drywall and paint.

We all make mistakes, and sharing these stories helps us learn from one another. It also might help to reduce the actual number of mistakes we all make.