Well, until very recently, I never would have thought about USB storage in the context of air conditioners, but… yeah, here we go.
Enter the York SSE controller board.
It’s cute. It’s needlessly complex. It’s actually as simple as it could be for being needlessly complex. Noot noot!
The board itself is a multi functional thing that apparently can be present in any of a few configurations. It could be in the condenser of a split system, inside the control box area of a rooftop package unit, or probably any of a number of other configurations that would surprise me.
In this case I was looking at one inside a condenser on a split.
This unit was newly installed as of a few months ago and it’s been a kinda rough start. Either right out of the crate or shortly after installation, one of the two temperature probes that connects to the controller went bad. It’s the one connected via two orange wires and the probe end is clamped and gooped to the suction line on the compressor. We had one near facility meltdown after the controller stopped the system in response to the bad sensor.
Once the sensor was replaced, I ran into another oddity wherein it was 90 degrees inside and 31 degrees outside, something was not right up there.
The way this system works is moderately odd compared to what I grew up with. On this system, the 24VAC control transformer is in the condenser on the roof (not entirely unheard of… but different). Down inside the building, the air handler has a Delta variable frequency drive in it controlling the blower. York, uh, “helpfully” password protected everything on this at the factory so you can’t even see how it’s configured, as you know, a job security measure. Gag me with a damn spork. It takes a constant current input setting the motor speed and a contact closure on the M2 terminal enables the fan. There’s also a relay output on the drive that goes… who knows where. The good news is, literally nothing on this drive will ever require you to adjust it as all the brains of the system are on the SSE board.
Fortunately there’s really nothing too special about that and if one did have to replace the drive, it wouldn’t be a total show stopper.
Anyway… I discovered that the factory configuration, which no one from our HVAC company (which is so great that we’re replacing them next month) touched, was not right. Not right at all.
First off… in this configuration, the indoor unit blower speed is to be set to “Fixed Variable”, which sounds about like Jumbo Shrimp, but it just means that the blower speed is set to a certain percentage on the SSE board instead of being controlled to meet a duct pressure setpoint for Variable Air Volume operation. The Fixed Variable option has set points for each cooling stage, assuming you have a multi stage cooling system (thermostat with Y1, Y2, …. wires). Well… this… doesn’t. It’s a single stage condenser, yet it shipped with some weird factory defaults in the SSE board that had it run the fan at a low speed, something like 40% for the Y1 stage. Being a single stage, this only had one yellow wire, so it only had a Y1… and it barely moved air. I went into the Details menu on it and adjusted the Y1 speed to 100%. Surprise, now it’s no longer hot on one side of the room it cools and cold on the other!
The more glaring issue was that it shut down when the outdoor air temperature was cold…. I found it had a default that cut it out when the outdoor air temp was below 45 degrees F. This could simply be disabled.
Before I made any changes though, I took a backup of the settings. On the middle of the board is a USB host port. Of course, the photo I took of it has a camouflaged USB drive stuck in it which is almost the same green as the board. It’s below and to the right of the big IC in the middle.
The instructions say to use a USB drive formatted with a FAT filesystem. I have this particular drive set up for legacy stuff – it’s got one partition just under 4 gigs in size, formatted to FAT. When it’s plugged in the display will say something like “USB OK / SCAN n” where n is the number of files on the drive.
You can then proceed to the Update menu and choose Backup, and it will dump a CSV file titled with the date and time. The date and time are not correctly set on this unit and I am not sure if there’s a battery backed realtime clock, so I didn’t bother trying to set it. It came up in 2002 or something.
The settings can also be restored from the USB drive. The file format is a strangely user-friendly CSV that will open straight up in Excel or OpenOffice Calc with all the rows and columns labeled. I was not expecting this at all. I was expecting to get an inscrutable binary blob that can be read and written only by some utility that requires you to have an old Windows XP system to support one particular version of Java that its user interface is coded in. I was very pleasantly surprised.
So all that being said, I recommend you take a backup of your configuration if you have one of these systems. If that board ever has to be replaced, this will save a LOT of time determining and re-entering the configuration. The user interface controls are those two buttons and the tiny joystick frobozz right below the LCD and it is not exactly pleasant to use at all.