Apartment: What system is this / thermostat replacement

I've moved into an apartment and am wondering what it does for HVAC. Here's what I know:

• Big central chiller up on the room (the building has to enter "summer mode" for cooling to work)
• Big blower/furnace box in my unit
• blower has two hoses that go into the wall and up, to roof? (doesn't look like refrigerant, may be wrong)
• blower control has four wires that I've pinned down to: fan, valve, compressor, and "R"

Now for the know-it-all DIY part. Long story but I got a wild nerve and decided to swap the thermostat myself. "How hard could it be?"

After some trial/error and having the heat come on a bunch I think I've got it. Directly switching the wires as per the instructions just made heat come on so I had to mess with it. Now, cool call will make it run the fan+valve+compressor, hot call will run the fan+heater. No more mercury thermostat from the 70's. Here's how I wired it to a Hunter thermostat:

Compressor to y1 24v/"R" to RH & RC Valve to Y/O Fan to G

("y1" and such are labels on the thermostat, I ignore wire color)

So It's keeping cool and I think I've wired it right side up. I can't explain it (although I have a theory) but the system doesn't seem to bang on/off as loudly, and when it comes off cool (fan only/no compressor for a minute) it has a gas/wheezy sound it didn't have before.

That's this weeks adventure in HVAC, thanks for any input on what kind of system I have and comments on my wiring. Hopefully I don't get kicked out of the complex.

submitted by /u/WholeNewDinosaur
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