The York Simplicity Smart Equipment SSE Board

Pingu nooting
Noot noot!

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.

Wiring cabinet on a condensing unit
Spaghetti Central

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.

Let’s rotate the board.

Several times in my adventures working on broadcast transmitter sites, I’ve walked in on a facility absolutely roasting itself to death because the batteries died in a digital HVAC thermostat.

Today was another one of those and it was the strangest. I’m not even going to try to explain what the hell happened because I don’t even know, but I can tell you that apparently, the Maxiva XTE exciters react by just turning everything into a bad game of Numberwang.

In all seriousness though, one exciter developed massive phase noise which led to viewer complaints of not being able to watch the channel, and the other drifted off frequency and wouldn’t go back. I wonder if it’s got packing foam glued over the oscillator like the old Apex?

Another day in paradise
Hooking up the GPS antenna along with the external 10 mhz reference… Look at this graph! But alas
This whole thing is uh, never mind, here’s some TCFW.
Picture unrelated, but I just love how this looks with translucent circuit boards.

BACNET Wack or Metasys Got Me HHHHHHHHHH


Oh hi. There’s a slightly modified screenshot of a page from our building’s Johnson Controls Metasys UI while it was trying to roast our morning show hosts and stage guys to death and I was trying to get it to kindly, you know, not.

This is for the studio air handing unit. It just blasts cold air into the studio and does not have heating features built in. Various people have asked me at times why the heating doesn’t work. It just now occurs to me I could show them this graphic – no heating coils, reheat, or connection to the gas furnace next to the air handler exist for a now obsolete reason: this studio used to originally be lit by a multitude of terrifying hot lights to the point that heating would not be necessary while the studio is in use. Here’s the air handler viewed from outside:

Chungoid with mad engineer in tall goth boots for scale
Supply fan – 15 horsepower!

A couple years ago I used to have trouble with the programming on this drive, but that’s long since resolved. The issue I was having was that it was just constantly getting a command to run at 00.00 Hz, which meant no blowy. A quick glance at Metasys showed me that it was calling for 100% chilled water flow to the coil and it was nice and cold inside the air handler, so I just hit battle short on the bypass there to get it going and cool the studio while I investigated. After the fan came up at 60.00 Hz (absolutely fearsome) it sucked one of the doors closed as I walked past it and tore my pants halfway down the side. Nice.

Anyway… Back to looking at the controls. The system cycled once like that, reaching the setpoint temperature and overshooting it slightly, then slamming shut the chilled water valve and letting the studio overheat again. When it had actually cooled the place down I went back up the roof and took the drive out of override, but now it stopped the fans too. Hmm.

This time I set Metasys in override. On each of those control parameters (return fan output, supply fan output, mixed air damper, and chilled water valve output) I could override them to nonzero values and the command would take effect! The only thing that was missing was any semblance of thermostatic control whatsoever. The system was just any degree between on or off I wanted… but once set like that, the studio temp would just drift up or down… I just about froze Tina and Courtney who were sitting right under vents. Aaaaaaaaaa! A call was placed at 8 am for the one and only controls tech in the area, who came out and spent several hours on the hellbeast.

Nyoooooooom. Note the movable blower inlet vanes, an artifact of a former control system that didn’t use VFDs.

After a while of scratching his head over the way our BACNET system was configured and how it was just spouting communication errors, the controls tech spotted one of these thermostats on the wall of the mechanical room with its display dark. Curious, we thought… I grabbed a meter and tested between the wires in it and found about 3.6 volts AC where there should be 24.

Sorry, I didn’t get a picture of the inside of it but it’s basically just like any normal thermostat, just with a BACNET connection in addition to the normal R, RC, C, Y, G, W, and Y wires. It basically just lets Metasys schedule occupancy and setpoints and monitor the status and temp. The menu system is maddening.

So I walked over to the electrical panel for the air handler it controlled and saw the breaker appeared to be on. I turned the breaker off and back on and the thermostat lit up and the blower started. 26.1 V AC appeared between R and C.

I agree with Scrappy.

At this point I went back into the studio, wound up the timer switch on the wall that serves as the manual zone occupancy override, and after a couple minutes, the blowers started and the water valve opened until the discharge air temp met the setpoint. (Yes… It’s even adjustable!)

So uhhhhh, what the heck? My only thought is that when that wall thermostat was getting 3.6v (why that and not zero???) it was just getting enough power to make the microcontroller or RS-485 line driver in there wake up and periodically yeet glitches into the BACNET void

The controls tech explained to me that it works like Token Ring. If the token falls out of a powered down thermostat in an empty mech room, does it make a sound? Really this all reminds me of something the Space Toilet used to do wherein you could mess up its canbus network and make the amplifiers blink on and off like holiday lights from hell.

Was it you? Did one of you take the shiny token back to line your nest?

A Payne in the butt

Do you ever look at something and wonder, “why in the actual hell?!”

This is one of the RTU (Roof Top Unit) air conditioners at one of the transmitter sites. It looks like a total pile of garbage but still works for some inexplicable reason. It was made by Payne – their logo still survives on one side but all other identifying marks are gone.

Bizarre condenser fan setup

Just look at that glorious weird ductwork. It’s next to the roof kerb where the ducts pass into the building, and then the ducts do a giant whirl around it. There might be an inline heater in the duct at the very end but who the heck knows.

Every now and then, it’ll yeet the evaporator fan belt. Last time, it yeeted the motor pulley too!

It looks like someone replaced the motor in this thing’s history and when they installed the new one, they found the shaft key didn’t fit and left it lying in the bottom of the cabinet and just tightened the set screw against the shaft. This worked until it eventually started slipping and the pulley spun on the shaft. I found it with the belt off and the pulley dancing around on the shaft. When I turned the power off, the pulley fell onto the roof. The shaft bore now measured 5/8″ on one side, 3/4″ on the other — it had become conical!

I got a new pulley and shaft key from McMaster and put it all back together, it works, but sounds a tiny bit more like a lawnmower. I don’t think it’s all that much longer for this world, honestly.

So on another note, Carrier got away from belt drive fans on their newer RTUs! Look at this monster that just went in at the other site..

Please ignore the terrible wire management. I’m trying to….

The evaporator fan, which moves the air to be cooled from indoors, is now a big vaneaxial type. It’s amazingly quiet too. Smaller vaneaxial fans can be found in 1 rack unit servers where they are most definitely NOT quiet, and larger ones are used in tunnel and parking garage ventilation.

I dunno, it seems like replacement of the Payne at the aux site is low on the priority list but I’m a little concerned that we’ll find it should have been higher on the list if we have to broadcast from there for a while over the summer. I can only imagine how many kilowatt-hours are being wasted via that pile of rusty crap. Somehow I’m imagining it being 10 SEER or less…


This post contains large amounts of angry hissing and swearing. You’ve been warned.


I was doing the weekly inspection checklist at the transmitter site when this….. Space Station Toilet….??? went thunk, plunk, and cycled out of Beam On. The display forlornly moaned of a low anode coolant flow alarm. I know the issue is with the flow sensor.

It’s in the middle of all this so I did not try to undertake the replacement single handedly. Look at this glorious mess!!!

But then my attention was drawn to the fact that it started getting warmer in the room… and it just kept getting warmer. Luckily, it was about 68 outside with a strong Delta Breeze, so I just opened all the doors and started to investigate the attempted thermal runway. On the roof I peeked into one of the large RTU (Roof Top Unit) air conditioners and saw a winter wonderland of ice. Hmm.


Not good. So why’s this thing icing up? It’s practically brand new! I called the HVAC company we have a service contract with and their dispatcher literally told me she was going to see if anyone felt like helping us out today. (No.)

Time to gather tools and investigate.

Ahhh! Copeland Popsicles!

Definitely a low head pressure situation… but why? Remember, PV=nRT even for insufficient levels of T[emperature], so maybe it’s just running too cold due to low heat input into the system. Let’s open up the other side…

Oh. You know, I don’t think that belt is supposed to be flopping around like a rubbery hula hoop.

Note three things in this photo: 1) motor sheave spinning. 2) fan sheave barely spinning. 3) harder to see but— water flying everywhere including spraying on that poor little ABB drive!

Click, power down, go gather more tools, climb up and down the ladder about a zillion times…

I set the thermostat below to system off / constant fan and properly tensioned the belt, which DerpCo HVAC’s techs do not know how to do… At all… then restore power.

No windy whirly. Just freezy fuckery.

The fan didn’t start. The little ABB drive’s cooling fan wailed, but it just wasn’t coming on. Why? Finally on a whim I twisted the red and green thermostat wires together and it ramped politely up to full blast with no slippage. Guess the thermostat just isn’t letting constant fan be a thing. That’s fine…

This economizer reminds me of that enormous gear Charlie Chaplin gets rolled across.

Slowly but surely, the room temperature started creeping down.

I always wonder if I’d get in trouble for naming and shaming DerpCo HVAC. They’re a large, probably national company, and are far more interested with their prime directives of union busting and bumping out any employees with seniority than they are with providing proper service to their customers. I hate dealing with DerpCo mostly, though they have *one* tech locally who actually knows what they’re doing.

Yeah sure you’re keeping up with maintenance

good jorb sweaty, totally glad we’ve been paying for a maintenance contract on this thing all this time

Upon having the staff working below complain they were pretty much freezing down there and looking in this confusing mess and seeing a suspiciously weak output air temperature… it was time to go investigate so I can tell the HVAC company how to fix it.

They do not successfully ever do diagnostics. I basically have to tell them what’s wrong and have them fix it.

Sometimes I wind up fixing it anyway because they have absolutely no clue how.

This is hopefully not entirely one of those.


wishful thinking.

but at least there’s no variable frequency drive involved. just a toasted drive belt that’s about two days from snapping off like an over-fried onion ring and leaving us shivering.

i don’t know i’m six days into what should have been a four day work week and my brain is just a bunch of aktivschaum.

anyway I found the thing having trouble lighting, short cycling, and periodically letting out gas farts because the “intermittent pilot” (a high voltage spark ignitor) was all fouled with crap… along with the venturis to the burners…. and pretty much….. everything


can i go home already?? youtube is recommending a video to me called “calm your anxiety”.

Apparently that heat exchanger isn’t original. We had another one of these units on which the heat exchanger cracked and Modine has entirely washed their hands of this series – no parts available anymore. The new one that was installed in its place is twice the physical size, makes huge banging and whistling noises, took ONE YEAR from order to delivery, and required a weird custom roof curb to sit in. Charming.

oh and the video is actually a pretty awesome lo-fi compliation

this is our solution

This got pretty badly stuck in my head yesterday for…. reasons

I figured out the root cause of the issue I posted about earlier on with the crazy fan circuit…. waaaait for it:

The pin was never securely inserted and latched into the housing of the fan connector! Welp. Lacking the correct tooling for this connector series (I have yet to be able to identify it!) I broke the rounded end off one of those plastic stirrer sticks from Starbucks and used it to prod the thing into place. It snapped in and I plugged the fan in and it’s happy again. Speaking of fans and drama, this greeted me with a rhythmic pounding noise from the office roof yesterday morning. I sent the HVAC contractor a photo of it and he arrived at the door at 9 AM laughing with a replacement propeller in hand. The cause of this one appeared to be that the “belly band” mounting Trane uses for the fan allowed it to slip down.

By design, these Trane units have a behavior that I consider to be just this side of “broken by design”. When the thermostat calls for cooling, the compressor starts and pumps gas (R-410A in this case) into the condenser, where it gives up heat into the metal finned tubes, condenses into liquid, and is sent to the output lines and into the building to boil inside the evaporator coil, cool the air down there, and come back to the outdoor unit as gas… the usual vapor compression refrigeration cycle. As the condenser heats up, the gas head pressure leaving the condenser starts to rise due to thermal expansion. You can hear the sound the compressor makes change as the head pressure rises, and I’m guessing the motor current starts climbing too. Once it rises to a certain point, a pressure switch trips and starts the fan, which cycles on and off based on the head pressure.

This causes it, in practice, to cycle in about 5-10 second intervals, repeatedly flexing and stressing every part of the nasty stamped sheet metal assembly up there.

The first time I encountered a unit like this in the wild, I thought I was hearing it repeatedly overheating and tripping a safety cutout. I had to ask an HVAC contractor if that’s normal. They said that (sadly) it is. Why?! I guess it might save a LITTLE power, but I don’t think it’s worth the reliability problems.

On a side note, my parents’ house had some ancient Sears “Good Neighbor” condensing unit that was made by Whirlpool, part of a retrofit from the 1970s or so (best I can find from trying to Google the thing). It claimed to be a two-speed condenser, but in reality, was a single speed compressor paired to a two speed fan that’d switch between high and low as needed based on the compressor discharge line temperature/pressure. It never outright STOPPED if the compressor was on. Yes, this was done… better… over four decades ago. Sigh.

It may be worth noting this was a pretty small R-12 system, couldn’t really fight the Florida heat well, but lasted a LOOOONG time. The condensing coil was much smaller than it is on modern high efficiency systems and I remember the temperature of the air coming out of that condenser being fearsome. You couldn’t comfortably touch the top of the unit after it’d been running.