hvac
When a low voltage HVAC unit cools a home do both W1 and Y1 circuits activate?
I've tested voltages when heating and cooling.
I'm trying to figure out what's happening.
Handler, Thermostat, and Outside Unit junction angle #1:
Handler, Thermostat, and Outside Unit junction angle #2:
Between Outside Unit and 3-Way junction (note reversing valve color change):
Thermostat:
You'll want to focus your attention to the wiring at the bottom of your last photo, that's where all the control wiring is.
Don't touch the wiring on the primary side of the transformer, as it's at line voltage and could cause a nasty shock.
If you clip the zip tie holding the bundle of wires together, you should be able to get a better look at what's going on. I can't tell exactly what's going on from the photo, so I'll explain what would typically be seen.
You should see a cable with a red, blue, green, yellow, white, and possibly brown wires. This is the cable that runs between the air handler and the thermostat. You should see another cable with a red and white wire (it may include other colored wires as well), which runs between the air handler and the condensing unit. According to the schematic, there should be a red and brown wire coming from the secondary side of the transformer.
The red wire from the transformer should be connected to the red wire from the thermostat, this is your Rc wire. The yellow wire (Y) from the thermostat cable, should be connected to a the red wire from the condensing unit cable. The blue wire (C) from the thermostat cable, should be connected to the white wire from the condensing unit, and the brown wire from the transformer. The green wire (G) from the thermostat cable, should be connected to the black and green wire from the air handler.
At the new thermostat you should have two cables, one from the air handler and one from the boiler.
Rh and Rc, if one exists.Rh. W.Rc.Y.G.C.NOTE: This is all based on typical wiring, your wiring may vary.
NOTE: Some thermostats may only use the Rh and C wires for power, so supplying an Rc/C combination may not work.
After checking with the building maintenance, the super said, because the building's main system is in "heating" mode and haven't switched back to "cooling" mode, the HVAC will automatically override and turn off the compressor. The building officially switched to "cooling" mode yesterday and my HVAC is operating as normal again. As it turns out, it is the building's main override.
Best Answer
Your thermostat repurposes W1 (call for first stage heat) as O/B (reversing valve) when in heat pump mode, instead of having a separate O/B terminal that's unused in conventional mode and using W1 to control the emergency/auxiliary heat. (Instead, W2 (call for second stage heat) is repurposes as AUX/E (auxiliary/emergency heat) when in heat pump mode.)
So, what you are seeing is absolutely normal in your case, merely peculiar to your model of thermostat. See page 6/PDF page 8 of the manual for details.