How do I switch on my central AC again?

6 years ago

last modified: 6 years ago

A family member put in our AC unit last spring and he came back out before the winter and wired everything for our furnace to start running. In order for our central AC unit to kick in he says he needs to come switch the wires back on thermostat but he refused unless we hire him to install a heat pump. I'm fine with my furnace and wood stove for winter. I know basically nothing about this, I'm just an average homeowner and farmer. Can someone look at this picture and tell me what needs to be wired to run my AC again? Does the red RC wire need to be hooked to yellow terminal? Forgive my ignorance. I just need this fixed my kids are suffering.http://imgur.com/gallery/I57G2RL

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Comments (4)

mike_home
6 years ago
It looks like you only have two wires so your family member must have moved the white wire from the Y terminal to the W terminal to allow the heat to operate. The wire needs to move back to the Y terminal for the AC to work. However the same change needs to be made at the furnace control board. Can you take a picture of the furnace control board wiring coming from the thermostat?
Brandon Cox
Original Author
6 years ago
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mike_home
6 years ago
The white wire connected to the top of the transformer may take you to the furnace control board. You need to find wires that are connected to terminals labeled W, Y, R, and G.

You should get an electrician to fix this electrical box. This is not safe if you have little children in the house.
formulaross20
6 years ago
You need more than 2 thermostat wires for the system to operate properly year-round. Nice family member trying to blackmail you! Sorry for that. Thermostat wiring is low voltage, 24 volts, so its safe for you to work on. This is a typical furnace and A/C wiring diagram:

https://www.hvachowto.com/wp-content/uploads/2019/08/Furnace-Thermostat-Wiring-and-Troubleshooting-Diagram.jpg

Get 18-6 thermostat wire from a box store, run the new wire between the furnace, A/C condenser and thermostat and connect the terminals as shown. The hardest part can be getting the new wire through the wall to the thermostat.