So I have a York diamond 80 furnace and the motherboard burned out so Lowe’s came and replaced it. I’ve been using the heater because it’s winter right now but the other day I accidentally hit the cool button on my thermostat and it sounded like something popped so I checked it out the wiring and realized the 3A fuse blew out. But I noticed that the thermostat wiring is different from before Lowe’s installed the new motherboard. the thermostat has (W with W) (G with G) (Y with Y) (R with RC) as it should because they never touched the thermostat but on the mother board of the furnace which is the part that Lowe’s switched out they have (W and G) jumped together and the rest of the colors match with the thermostat before they installed that motherboard I knew that W was by itself and G was by itself I don’t know why they would jump W with G together but can that cause my unit to be faultyenter image description hereenter image description here

  • Hello, and welcome to Home Improvement. It's hard to understand what you mean; some pictures of the thermostat and furnace ends of the wiring would help. – Daniel Griscom Feb 6 '19 at 13:15
  • "they have (W and G) jumped together" - I'm not seeing that. All I'm seeing is the green not hooked to your furnace, and the blue is on the G terminal at the T-stat for some reason. What's it say behind the green wire? OT SEL ? – Mazura Feb 6 '19 at 19:39
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    What make and model is your thermostat? – ThreePhaseEel Feb 6 '19 at 23:44
  • They put the blue in the (G) section on the thermostat but the motherboard the (G) is connected with the (C) I thought those had to be separated that’s why the motherboard has a section for (G)? – Michael Torres Feb 7 '19 at 3:44
  • On the thermostat the green wire is connected to (not used) – Michael Torres Feb 7 '19 at 3:44

It's definitely wired wrong. You need 4 wires to your stat R to Rc and Rh or R and Rc (it's hard to tell from the picture) bottom line is all three R's go together obviously using the red. W to W using the white. G to G using the green. Y/Y2 to Y using the yellow. That's it! Get that blue one outta there. The other 2 conductor cable is for the A/C one goes to C and the other to Y/Y2

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