Thermostat wiring problem?
Question:I foolishly didn't check the wiring when replacing an analog thermostat with a digital one. Now the Air Conditioner won't come on. There are 5 wires two red one green,blue and white. How can I ring these out? Or is there a standard? Also it is a forced air heater.
Answers:
normally it would be like this red is hot R terminal..one red is for heat RH ..one red is for cool RC.green is fan G terminal.white is heat W or W1 terminal ..and in this case i would assume blue is for cooling Y terminal .what you might need to do is go down to the air handler and find out what wire connects where..if both reds wires tie together at the air handler then you would be in good shape as you could just put both of these under the r terminal on the thermostat.this would be the case if your old thermostat had a rh and rc terminal to connect the red wires two...and they were not jumpered together.and easy way to find out is to just take either red wire one at at a time and see if will turn the inside fan on when you touch either red wire to the green wire...if both red wires will cause the fan to come on then put both of these under the R terminal.if this works then the blue wire should be for cooling...put this under the Y terminal on the thermostat once your sure both red wires will turn fan on.if both red wires will not turn fan on then you will have to go to air handler and find out what color wire from your thermostat connects to the corresponding wire or terminal at your air handler...
You may have blown out the transformer or the small fuse that goes to it.
One way to find out, momentarily touch one of the red wires to the green and see if you get a small spark (arc), if not, try the other red, if you get a spark or hear the blower try to come on, then that red is the HOT (+), and green is usually FAN/BLOWER, white is usually HEAT, blue is probably COOLING, but sometimes Common (-), my guess is one of the red wires is common (C) on the digistat.
one red is hot, the other may be a/c compressor
He's right, as long as who ever originally wired did it correctly. Definitely check the wiring on the furnace.
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