Need assistance with Decoding the wires from our HVAC unit to our Thermostat

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  #1  
Old 05-27-14, 03:08 PM
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Need assistance with Decoding the wires from our HVAC unit to our Thermostat

We upgraded our thermostat last October and didn't record the wiring or save the old thermostat. Our heat worked great, but now the A/C doesn't turn off and we've deduced that it's a wiring problem.

We have a Carrier Performance 80 that we can't find online diagrams for and when we emailed the picture in the unit to my father-in-law, he says it's missing information.

The new thermostat is a Honeywell RTH2300.

The wires inside the wall are Orange, Green, Red, White, and Blue, but the Blue wire isn't connected to anything on the HVAC end.

There are two groups of wires coming from the HVAC. Green and Yellow. Yellow, Green, Red, White, and Blue. The two yellow wires are connected. The green wire paired with the yellow is connected to the orange. The Green paired with the other wires is connected to green, red to red, white to white, and blue is hanging out.

Unfortunately, the image uploading keeps failing.
 
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Old 05-27-14, 03:31 PM
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I'm somewhat confused as to how many wires are going to the thermostat. You mentioned 2 yellow and 2 green wires. However, assuming the wire colors are connected to the furnace in the conventional order, here are what the wire colors are:

Red is the 24VAC going to the thermostat, coming from the transformer
Yellow is the wire going to the compressor (outside A/C) unit and controls it's operation
White is the wire that controls the furnace operation (heating unit)
Green is the wire that controls the operation of the air handler (blower)
Orange or Blue is used for heat pumps and controls whether the unit is operating in heating or cooling mode

Whether your system is wired per the "standard" color coding convention is anybody's guess, but if it is, the above information tells you what each wire does.
 
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Old 05-27-14, 03:57 PM
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At T.stat
Orange = Y
Green = G
Red = RC/Rh
White = W/B
Blue = no connection

You need to explain a little better what your connections are.

"There are two groups of wires coming from the HVAC".... What's the HVAC ????

There should be one cable from the thermostat to the furnace and one cable from the furnace to the compressor unit.

http://www.doityourself.com/forum/el...-pictures.html
 
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