Need some wiring help!


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Old 12-15-14, 05:43 PM
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Need some wiring help!

Hello, new to the forums. I searched a lot but cant seem to find any solutions to my problem.
Its really a long story, but to make it quick here is what happened. Been in the house for about 2.5 years. About 6 months ago I lost power and after that had some problems that I attributed to a bad thermostat measuring the wrong temp. All was great. Winter hit and I noticed that the ac condenser fans running even when I had the heat on, then, even when I had everything off. After a lot of reading, I replaced the contactor on the outside unit. No luck.

But here is where im at now. I learned that when all of the wires are disconnected from the thermostat, it still ran. However, there are 2 sets of wires that are connected to eachother. Once these are disconnected, the fan finally shut off!!!!

Here are pictures of the wiring. When I put in the new thermostat, i copied EXACTLY the previous thermostat wiring. The weird thing is there is 7 wires, with 2 whites and 2 reds.
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the 2 reds were wrapped around eachother as well as one of the white ones and the yellow ones. When the white and yellow are connected, the fan comes on about 5 minutes later.

Thanks for any help with this. If Im wrong and its not the wiring, please tell me. The weird thing is that it seemed to work fine before.
 
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Old 12-15-14, 06:55 PM
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Welcome to the forum!! Your thermostat appears to be a Filtrete 3M-50, correct? To better assist and sort out the wiring we will need the type of system and model numbers of the inside and outside units.

The weird thing is there is 7 wires, with 2 whites and 2 reds.
Is your system a heat pump? Because there are two reds and two whites it is probably because there are two thermostat cables coming out of the wall: one cable with 5 wires and one cable with a red and white.
 
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Old 12-15-14, 07:01 PM
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If the second red and white wires run to the outdoor unit they are incorrectly connected.



The outdoor unit connects to Y and C, not Y and R.
 
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Old 12-15-14, 07:40 PM
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thanks for the help. I believe that does have a heat pump. I dont know the model of the inside unit. ill be able to get it tomorrow. the outside unit is Carrier model 38BRC042340.

There is actually about 14 wires coming out of the wall, those were the only one being used.

And yes, you were correct on the thermostat model
 
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Old 12-15-14, 08:13 PM
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I believe that does have a heat pump.
No, based on the model number you provided, it is a conventional a/c condenser. Here is a link to the installation manual:

http://dms.hvacpartners.com/docs/100.../38brc-5si.pdf

There is actually about 14 wires coming out of the wall, those were the only one being used.
You will only need 5 of those wires as diagrammed by Houston204. It may take some time to verify exactly which ones are actually connected at the air handler and condenser.
 
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Old 12-15-14, 09:14 PM
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I would expect that you only need to move one of the red wires to C.
It would be the red wire from the condenser outside.

It should be the red wire in the bundle that does not include the green wire on G.

An easy test would be removing one red wire and taping it off.
Reconnect the stat and try to run the fan.
If the fan runs, connect the taped off red wire to the C terminal along with the wire already there.

(condenser red and white are interchangeable so you can leave white with yellow at Y)

I have seen the condenser and furnace wires run to the stat before but it always makes me feel that someone was trying to use less wire.
 
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Old 12-16-14, 05:16 PM
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I found the two wires that are just red and white, and I assume those go to the condenser. The problem with what you said is that when the white and yellow are connected, the condenser fan runs no matter what, even if the stat is not hooked up.
 
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Old 12-16-14, 05:25 PM
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Did you move the Red wire that goes to the condensor to the C terminal ?
 
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Old 12-16-14, 05:27 PM
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where does the blue wire go when I do that?
 
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Old 12-16-14, 06:13 PM
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Also on C. The blue wire probably goes to the t'stat C terminal.

That t'stat has nice terminals. You can put two wires in the same terminal at the same time.
 
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Old 12-16-14, 06:30 PM
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thanks, to clarify, Im putting the red wire from the condenser to the C with the blue. the white from the condenser is connected with the yellow and then connects to the Y. The white wire by itself to the W, the green to the G and the other red to the RH which is bridged to the RC? Correct?
 
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Old 12-16-14, 06:31 PM
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Yes........ that should be correct.
 
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Old 12-16-14, 07:24 PM
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well something went wrong. I wired as described below. The inside fan kicked on for about 30 sec then off. Now there is no power getting to the thermostat. I swapped it out with a basic thermostat i have lying around that doesnt have batteries (that has worked here before) and no power whatsoever. No breaker flipped. Not sure what to do now.
Seems like I messed something up
 
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Old 12-16-14, 08:38 PM
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Sounds like you put the wrong red wire on C.

Check inside the indoor unit for a popped low voltage blade type automotive fuse.

If the indoor unit is also a Carrier, 3 amp for gas heat or 5 amp for an air handler.

An example of the board on a gas furnace...


An air handler...
 
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Old 12-17-14, 12:23 PM
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First, thanks for all your help. You were right, the fuse was blown. while up there I took a close look at the wiring. Heres what I found, the white wire coming from the outside condenser connects to the yellow wire at the thermostat and the red wire from the condenser to the blue wire. Then 5 wires go from the upstairs unit to the thermostat. Im not sure where the extra white and red wires are coming from. Not sure if this picture helps but heres what it looks like up there.

When I hook up the wires as Im supposed to and completely leave out the extra red and white, the unit appears to be working right. Any ideas on what these extra wires go to?
 
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Old 12-17-14, 05:52 PM
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More than likely you would have to trace that cable to see where is goes but I have two ideas.
#1 - It goes to a humidifier.
#2 - It goes to a condensate pump for the overflow switch.

Do you have either or both ?
 
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Old 12-17-14, 07:23 PM
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yes, Im pretty sure I have both. the overflow switch though I was wired in upstairs to the other wiring so I guess its the humidifier. If so, where would those wires go?
 
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Old 12-17-14, 07:46 PM
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Since you have both I'm leaning towards the condensate overflow switch. When the tank is not full of water and is not overflowing..... the switch is closed or a dead short. That's what you have happening. The switch goes in series, or breaks, the Y line to the compressor.
 
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Old 12-17-14, 08:59 PM
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interesting....Ill get back up there tomorrow and have a look but that makes sense. I really appreciate all of yalls help
 
 

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