Need help with getting a over flow switch that needs installing on a ac unit. Used to turn off ac if overflow backs up so there is no water damage.
Ac is above furnace unit in a hall closset area.
Email fd150 at hotmail dot com

I suggested moving the question to H&A/C. I don't think there is much to it, but I may miss an important detail. You may need to go to a HVAC supply to buy a small float switch. Install the switch in the overflow pan if you have one. Wire the red wire to the thermostat to the common and NCC. Thus, if water backs up into the over flow pan, it trips the switch, opening the contacts shutting power off to the thermostat. If you wired it to the yellow wire, the blower would still run.

The best thing to do is to buy a Condensate pump and set beside you Evap coil, It will consist of a water box and a electric pump and a float and switch. The pump will need to be connected to 120 volts power with the power cord provided. There will be two wires coming off the float switch. You need to find one of the low voltage wires going to the condensing unit, cut one of the wires then connect one end of the wire you cut to one of the wires coming off the float switch, connect the other end of the wire that you cut to the other wire coming from the float. As the AC drains the float will rise and when it raises the float high enough the water will be pumped out of the water box. If the pump fails to come on then the float rises higher and breaks the connection going to the condensing unit and will stop any further water to be collected in the box.