adding central air/thermosta wiring


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Old 07-13-08, 01:45 PM
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adding central air/thermosta wiring

I have a question I would like to ask. I was given a central air unit when a friend upgraded. I want to do all the work myself except leak checking and charging the system. I ran all the copper and wiring. The only thing I'm lacking is the thermostat hookup. This is where I need assistance. I know the themostat wiring (24volt) needs to run through the transformer in my furnace. I can't find a wiring diagram to guide me as to what terminals to connect to, then run up to the new thermosta. My furnace is a Trane XL90. There is terminal block that is marked and has the two wire running up to the old thermosat (I replaced the old mercury switch with a digital one that runs both heat and a/c, the old one mercury switch just ran heat) , but I didn't want to just start experimenting without some guidance.
 
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Old 07-13-08, 01:52 PM
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Cost!

If you miswire it - it will cost hundreds if not a K bill - even with advice here. If you call a tech to wire it...you will be safe. Havent you saved enough money by doing all the hard stuff yourself? Let a tech wire it and dont burn up the boards/transformer/t-stat/fuses, not to mention the frustration...oh god the frustration!..ect!

 

Last edited by The Real Deal; 07-13-08 at 02:25 PM.
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Old 07-13-08, 03:32 PM
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Agree with Real

But, if you post model and serial numbers for both units (in and out) I maybe able to get original literature from Trane for you.
 
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Old 07-13-08, 04:43 PM
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Trane furnace

Thanks for your responses, I appreciate it. Anyway, as far as the heat pump, the only legible numbers on the data plate are: Goodman mfg. G0181770080.
There is a wiring diagram inside the access panel regarding the proper wiring on the heat pump. The evaporator data plate reads: Model GH365 NV324 24-ZJ-L/C, s/n 3/9-012347.
I can't read the manufacturer's name though.
The furnace reads Trane 90 XL model appears to be 8LU080K94283. s/n reads C06507447 I did find the Trane's operators manual online but nothing with wiring diagrams.
 

Last edited by spotstealer; 07-13-08 at 04:49 PM. Reason: additional info added
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Old 07-13-08, 05:54 PM
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Goodman can't help with - yet.

Trane, came up with nothing. Either pre 1995 or bad numbers.

Did email Trane with numbers to see what can be found.

Keep you posted.

What are trminals in the furnace for the tstat?

But you have a mismatch there, not good.
 
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Old 07-13-08, 07:45 PM
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IF the furnace has a terminal strip where the existing thermostat wiring is connected it should have terminals marked C, Y, G, W, R (in any order) and the existing thermostat would be connected to the R and W terminals. You will need to connect additional leads between the thermostat Y and G connections at both the thermostat and furnace.

The condensing unit will have two low voltage connections and they may or may not be designated by terminal. They will connect to the Y and C terminals on the furnace.

The connections are:
C= 24 volt AC common
R= 24 volt AC supply
W= heat control
G= blower control
Y= cooling control
 
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Old 07-13-08, 07:58 PM
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I came up empty on the goodman... YOu said heat pump... That will need a t-stat to control heat pump.

What the letter codes did the wire diagram say to wire?
 
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Old 07-13-08, 08:34 PM
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Okay, ignore my previous post if this is a heatpump.
 
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Old 07-14-08, 03:32 PM
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Had luck at Trane but He printed and faxed the manual, not email.

I'll try again.
 
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Old 07-14-08, 03:44 PM
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data plate

Thanks again for all the information. The data plate on the A/C unit was unreadable, the only numbers were the ones I wrote below. The data plate said Heat pump, then Central Air Conditioning unit both with the same numbers. I talked to the guy I got it from and he said it was a central air unit. The terminal block on the furnace is as stated below by furd. Looking at the terminal block in the furnace, there is no back side connection on the Y terminal, that is what is throwing me off. I'm calling for the servicing tomorrow, I'll let them peek at it before I have an oops. Thats all I need to is give my wife more ammunition! I'll post once I get it right, thanks a bunch!
 
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Old 07-14-08, 04:26 PM
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No back side on Y terminal

because it's a connection point between stat and outdoor unit.

Stat connect to terminal board. Condenser connects to Y and C, or B common.
 
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Old 07-14-08, 04:48 PM
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Somtimes my senility overwhelms me

While I couldn't find the furnace manual with the provided serial number (model was incorrect), my friend at Trane did. Since he faxed rather than emailed I thought oh well, try again.

Having the Pub No. is a completly different search.

Click on the button link titled TUX2_TDX2_PDT.pdf here:

http://jarredsdad.embarqspace.com/#/welcome/4529420987

That manual matches furnace serial number provided.
 
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Old 07-14-08, 06:48 PM
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Y connection

Jarredsdad, thanks!
For both the link and the connection tip. Sometimes you can't see whats right in front of you, thats exactly what I see now. I 'made the connection' now!Thanks again!
 
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Old 07-14-08, 07:35 PM
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Originally Posted by spotstealer
Sometimes you can't see whats right in front of you,

Hey, we have brain farts too. Boy what a thread that would make!

Don't forget, certified tech for sealed system final.
 
 

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