So I live in San Antonio, TX, and I'm an air conditioning contractor. I get calls from all kinds of people, but one I got this past week probably stands out quite a bit.
Anyways, the first thing that stands out about this call was that it was from a post office rental management company. That's a real estate company that manages the properties post offices use. This particular company manages about 5 properties within a 30 mile radius of San Antonio, and over 600 properties nationwide.
So this guy named Sean calls me from New York or someplace like that. He says he wants a 2nd opinion about what needs to be done with an air conditioning unit that another contractor says needs to be changed out. He told me the other guy advised him it's time to change it out. So I agreed to go check it out.
This post office is off of West Avenue in San Antonio, which is just about a mile and a half from my house. So, I drove on over there to check it out, took my tools out of the truck, hooked up the gauges, took the service panel off the unit, looked up and saw the other contractor walking up to where I was. He seemed just as surprised as me as to why the other guy was there.
Well, we introduced ourselves and started talking about the unit and what's been going on with it. He was a pretty friendly fella, so it wasn't hard to strike up a conversation with him. He told me that he had installed that unit a few years prior, and had another unit on site that he was ready to install since this one had gone down. He said he remembered that the last compressor was on the way downhill, but he couldn't remember exactly what he had diagnosed.
You see, this is an old, 15 ton York unit that has two compressors that work in stages. What that means, is that one compressor is used as a primary, and the other is an auxiliary compressor. The primary runs all the time, and the auxiliary only kicks in at times where the load is too substantial for the primary, or even if the primary compressor overheats. In other words, the auxiliary compressor doesn't work as hard or as much as the primary. Now, I don't know everything about this particular brand unit, so anyone wanting to teach me something can chime in. Well, the primary compressor was supposed to have already gone out on this unit, so it was disconnected, and the unit had been working off the auxiliary unit only for the past few years. Since the unit is already a dinosaur, it would be no surprise if it stopped working at all.
I explained to the other contractor why I was there, and that I had to do my due diligence with the unit, and check it all out. He understood, and kind of went along with me as I checked it out. Well, the first thing I did was to see if I could test the primary compressor for an open circuit. Since it's a three phase unit, I couldn't just ohm it out. The problem was that I wasn't able to test it as open. It came up as a good circuit every time and way I tested it. Well that didn't make any sense to me, so I reconnected it. I then flipped the breaker, and low and behold, it worked!
The other contractor seemed just as amazed as me. He swore that it wasn't working the last time he was there, otherwise he wouldn't have unhooked it. All I knew was that it was working now. So, I left it working, and called the management company again to let them know what I had found. Even though I figured it was one of those things where the other contractor may not have been wrong, I think he felt like someone wanted to blame him, so he quickly disappeared.
As it turns out, the other guy wasn't necessarily wrong. I think he just may have found it very hard to diagnose the problem because of the safety mechanisms York puts on their units. All signs pointed to the compressors being out, but it was almost impossible to verify this with traditional tests. I'll probably give the guy a call and tell him what we ultimately learned so if he ever runs into one of these units again, he'll be ready.
The ultimate problem will have to wait for later though. My carpal tunnel is acting up. I'll finish this later.