I cut my A/C thermostat wire with my weedeater. I reconnected it, but my A/C still won't work. Why not?

Question

I called an electrician, and he said just reconnect it. I did. The A/C cut off immediately when I cut the thermostat wire. Nothing appears to be disconnected. I even bought a new length of wire, attached it, but with no luck. My thermostat is just an old-fashioned, non-programmable thermostat. I pressed a button inside the wiring box, and my A/C comes on, so it appears that the problem lies with the wire. Please help me!

Answer 1

Ok, this is the deal, when you cut out the t-stat wire and you cut them off all at once with pliers, you must of made contact with the common wire and the live (24v) wire. What you need to do is replace your step down 24 volt transformer. That's the power to your t-stat you must of short it out. If you have a volt meter, check for voltage coming out you got to have 24 volts coming out. If you get no voltage then replace it.

Answer 2

I don't think that was the thermostat wire unless you were weed eating indoors. The thermostat wires run to the inside control unit. If you cut a wire outside it's something other than the thermostat. I think you need to call an AC technician.

Answer 3

check your fuses when cut possible grounded out if they came in contact with each other

Answer 4

Yes, for electrical work you need to use a meter to do it well, to check if you lost the voltage or where.

Many control boards these days fuse the 24volts circuit to protect the boards. You likely blew that when you cut the wires.

They use a little 3 amp blade type automotive fuse for that and it is on the board. Check the diagram on the blower door, main cover, or the cover for the board on the furnace or air handler and usually there is a layout diagram. Sometimes they are a little hidden.

Good Luck.

Answer 5

That button you touched is called contactor and you manually activated it and that's why A/C came on, but as soon as you released it it shut off, wright? As Top contributer said you more likely shorted out transformer. Transformer supply entire system with 24 volts and needs to be replaced or possibly has reset button, but in many cases it doesn't have one. If you connected all wires correctly, which is easy, all same colors, then look in to transformer replacement or reset.

Answer 6

HVAC Tech.Could be the wires from the thermostat got twisted together and shorted the 28volt transformer (fried it). Some units have a separate fuse for the protection of the transformer.  Also, Where you spliced the wire there might be a break you cant see, you need a meter to check it. Ofcourse thermostat wire going to the outside unit need to be protected from dogs, kids,weedeaters, and lawnmowers.