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Phil
Phil, Mechanical Engineer
Category: HVAC
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Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have an xl824 thermostat and a single stage furnace with a

Customer Question

I have an xl824 thermostat and a single stage Bryant furnace with a carrier air conditioner. First, there is no blue wire in my wall but there are 2 green wires. I have r, 2g, w, y. After wiring according to the Diagram 11 when I put the display screen on the mount. The screen stays black. Can you help.
Submitted: 2 months ago.
Category: HVAC
Expert:  airheatman replied 2 months ago.

1. If you are replacing a thermostat, tell me what all wires went to on old thermostat.

2.If not replacing, just installing, we will need to look in the furnace and se what each connects to in furnace

Customer: replied 2 months ago.
Replacing. Red to R on old thermostat. Yellow to w. Yellow to y. Green to g.
Expert:  airheatman replied 2 months ago.

OK now in original question you stated you have 1 red, 2 greens, a W and a Y

IN second reply you state Red,2 yellows and a green.

Help me out here.I am depending on you to be my hands as eyes as we go through this.

Customer: replied 2 months ago.
On the xl824 I have red to rc. With jumper to rh. Yellow to y1. Green to g. Other yellow to w1.
Customer: replied 2 months ago.
There is no white wire in the wall. The 2nd yellow was hooked to W in the old thermostat.
Expert:  airheatman replied 2 months ago.

OK thanks.

So you have the RED to RC and RH that is good

The yellow that went to Y to Y1 that is good

The yellow that went to W to W1 that is good

The green that went to G to G That is good

Now do you have an unused wire we can use for Common (B/C)?

Customer: replied 2 months ago.
Each wire in the wall has an unused black wire and the extra green wire is in the wire that has the yellow wire that is hooked to w1.
Expert:  airheatman replied 2 months ago.

On old thermostat did you have either a C terminal or a B terminal and if so what wire was connected to it?

Customer: replied 2 months ago.
No wires were connected to B or C. This thermostat also ran by batteries if that makes any difference.
Expert:  airheatman replied 2 months ago.

OK the XL824 requires us to have 24 volts where some thermostats are battery powered.

This means we have to have a wire from the Hot side of transformer in furnace as well as the COMMON side of transformer.

So what we are going to have to do is use one of those "extra" wires and connect it to B/C on thermostat and "Common" in furnace.

If you can give me model on the indoor furnace I will help you determine where to connect that "extra" wire in the furnace.

Customer: replied 2 months ago.
Bryant - 925SA60100E21A-A
Expert:  airheatman replied 2 months ago.

Excellent give me a few moments to fin da manual on furnace

Customer: replied 2 months ago.
Ok
Expert:  airheatman replied 2 months ago.

OK remove the panels on furnace and you will find a computer board inside where all of the thermostat wires connect.

On that board you will see the terminals marked W,R,G,COM and Y.

The yellow you have connected to W1 at thermostat should go to W

The Red you have connected to RC/RH at thermostat should go to R

The Green that you have connected to G at thermostat should go to G

The yellow you have connected to Y1 should go to Y.

Then we will connect one of the blacks or the extra green to B/C at thermostat and to CO

Mm at furnace board.

Se link below

Expert:  airheatman replied 2 months ago.

Should say "Then we will connect one of the blacks or the extra green to B/C at thermostat and to COM on furnace board

Customer: replied 2 months ago.
Does it matter which black?
Expert:  airheatman replied 2 months ago.

Makes no difference.You just have to verify you are using black from same set of wires in both places

Customer: replied 2 months ago.
Guess I will use the green then since there is only 1 extra green. There is already a red and white connected to com. Is this ok?
Expert:  airheatman replied 2 months ago.

Yes one goes to the outdoor unit.The other may go to a humidifier or something. Just add the green and connect other end to BC at thermostat

Customer: replied 2 months ago.
All done. Still no power to display screen.
Expert:  airheatman replied 2 months ago.

OK look on that control board and see if there is a small 3 or 5 amp fuse. Remove it and see if it got blown when you first started messing with wires.

http://i.imgur.com/pKP74Wg.png

http://i.imgur.com/kYe4Epz.png

Expert:  airheatman replied 2 months ago.

Location on your board

Customer: replied 2 months ago.
Not blown.
Expert:  airheatman replied 2 months ago.

Do you have all panels back on furnace? If so do you have a volt meter so we can do some troubleshooting?

Customer: replied 2 months ago.
No I don't have the panels back on. Yes I do have a volt meter.
Expert:  airheatman replied 2 months ago.

You must put panels back on to have power to thermostat as there is a door switch held in by blower panel.

Expert:  airheatman replied 2 months ago.

Put panels on and we will go from there if still no display

Customer: replied 2 months ago.
Door is on. Still no power.
Expert:  airheatman replied 2 months ago.

OK remove panel and hold door switch in, Then check between R and C on furnace board and see if we have 24vac between them

Customer: replied 2 months ago.
Of course my voltmeter isn't working but when I hold in the switch I get a yellow status light on the status code led.
Expert:  airheatman replied 2 months ago.

We will need a working meter to troubleshoot. Put panel back on.Go to thermostat and touch the red and green that is going to G and see if blower comes on

Customer: replied 2 months ago.
Can I get back to you tomorrow?
Expert:  airheatman replied 2 months ago.

Absolutely