Need help installing Trane thermostat

[integlikewhoa]

Ok, on aux heat the answer is no. Don't have that feature. The air handler model is:

4TEC 3F4BB 1000AA which I inappropriately identified as the "heat pump". Wasn't thinking clearly.

I can open it up and take pictures later today. There is no wiring diagram on the outside. Would be nice to find some documentation on the web so will look there.

Thanks for everything.

Your model number is off by one and google gave me a hard time about it. LOL        48 not 4B in the middle which is the ton size of your unit which is 4 Ton by the way.

So you have a TRANE  4TEC3F48B1000AA

Here's a online manual, but you should find when you open the big access door on the unit it's also mounted on the inside.  ( I also have a trane air-handler, but different model)
https://www.trane.com/Commercial/Uploads/Pdf/1111/2_4tec3.pdf

I have attached the wiring diagram below, one un molested and the other I have circled the 120 to 24v transformer and traced over the common wire as it leads down to the connection block. The wire is BLUE inside the Air Handler and you'll notice coming out the transformer the power wire is red with a fuse 5 amp fuse before it gets to the connection block.

These two wires ultimately have to get to the RC/RH and C on the thermostat to power it up.

Judging by the info you gave us and the and the old thermostat connections I don't think any of this below really applies but I'll throw it out for more info or to double check anyways.

I'm very curious about the BLUE wire in the wall hooked up to "O" on the thermostat and would like to have more info on which wires go to where when you open the door on the Airhandler. Just want to make sure it doesn't go to the Blue wire inside the Air handler. 

Reason is because without a heater and only single stage cooling and heating you really don't need 6 wires. In my Arizona house they powered the "O" and the "W" heating together (inside the air handler they were twisted together). They did this since there is no actual heater and anytime to turn on the heater "W" it powers the reverse valve at the same time and only at the same time. I can only assume yours might be the same, but don't think so based on your first post wiring description.

[GoingGreen]

While searching the web for an electrical diagram of my air handler I quickly discovered a wealth of information about thermostat wiring that applies to heat pumps. YouTube has many videos produced by HVAC technicians. I got a lot out of viewing the videos.

[integlikewhoa]

While searching the web for an electrical diagram of my air handler I quickly discovered a wealth of information about thermostat wiring that applies to heat pumps. YouTube has many videos produced by HVAC technicians. I got a lot out of viewing the videos.

So did you get it installed?

[GoingGreen]

Yesterday I opened the air handler cabinet and did not like what greeted me. A tangle of wires connected with wire nuts. I'll try to capture a clear photo to attach.

Looking at the existing cabling I am changing my mind about installing a new cable, instead I will just have to find the correct wire to route to the new thermostat, if needed. I did find the air handler documentation pasted inside the cover. Sorry about the mistaken part number I originally posted. 

Integlikewhoa, I am not following your comment about the diagram.

"I have attached the wiring diagram below, one un molested and the other I have circled the 120 to 24v transformer and traced over the common wire as it leads down to the connection block."

Did you forget to attach the diagram? By "connection block" I am assuming you mean the "polarized plug".

In any case if what I now understand you saying is true the point is moot. I don't need six wires.

Tracing the blue conductors I see the connection to the polarized plug (6) from a relay contact inside a closed housing.

There are two identical five conductor cables: one goes to the thermostat and the other leads outside. Colors are white, green, yellow, blue and red.

The blue conductor in the thermostat cable is connected to the white conductor in the outside cable.

Notes:
photo 1445 is the Braeburn connector block
photo 1440 v2 is a cropped version of the polarized plug and associated cabling

I am running up against limits of photo size I can post. Let me know if these photos help.

[integlikewhoa]

Integlikewhoa, I am not following your comment about the diagram.

"I have attached the wiring diagram below, one un molested and the other I have circled the 120 to 24v transformer and traced over the common wire as it leads down to the connection block."

Did you forget to attach the diagram? By "connection block" I am assuming you mean the "polarized plug".

No I attached 2 files in that post and as you have found they match the one in your 2nd picture.

There are two identical five conductor cables: one goes to the thermostat and the other leads outside. Colors are white, green, yellow, blue and red.

I'm assuming the one lower in the pic is the one going to the thermostate. The higher one is going outside to the a/c unit.

The blue conductor in the thermostat cable is connected to the white conductor in the outside cable.

Are you sure it looks like in the picture the blue in the air handler is wire nutted to the blue going to the inside thermostat. Hard to tell as the red wires are in front blocking the picture.

I am running up against limits of photo size I can post. Let me know if these photos help.

And you post one or two more pictures with the wires moved around a bit to show me which colors are going to where from both the outside ac and the thermostat

Also the way they have it wired it doesn't look like you'll need the 6th wire and it looks so far (waiting for pictures to confirm) that the 24C wire is already hooked up in the air handler to the blue going to the thermostat. So it just might be a matter of putting blue to the 24c in the thermostat and your done.

I specifically right now need to see better shots of the which wires are going to the outside a/c unit. The white wire coming from the thermostat (the heat wire) is wire nutted to?

[GoingGreen]

Integlikewhoa, I am not following your comment about the diagram.

"I have attached the wiring diagram below, one un molested and the other I have circled the 120 to 24v transformer and traced over the common wire as it leads down to the connection block."

Did you forget to attach the diagram? By "connection block" I am assuming you mean the "polarized plug".

Today your attachments are showing clearly. There must be a bug in the forum software.

No I attached 2 files in that post and as you have found they match the one in your 2nd picture.

There are two identical five conductor cables: one goes to the thermostat and the other leads outside. Colors are white, green, yellow, blue and red.

I'm assuming the one lower in the pic is the one going to the thermostate. The higher one is going outside to the a/c unit.

Yes, this is correct. 

The blue conductor in the thermostat cable is connected to the white conductor in the outside cable.

Are you sure it looks like in the picture the blue in the air handler is wire nutted to the blue going to the inside thermostat. Hard to tell as the red wires are in front blocking the picture.

Yes, this is the case. However, the blue and white conductors are cross connected in the two cables.

I am running up against limits of photo size I can post. Let me know if these photos help.

And you post one or two more pictures with the wires moved around a bit to show me which colors are going to where from both the outside ac and the thermostat

Also the way they have it wired it doesn't look like you'll need the 6th wire and it looks so far (waiting for pictures to confirm) that the 24C wire is already hooked up in the air handler to the blue going to the thermostat. So it just might be a matter of putting blue to the 24c in the thermostat and your done.

I specifically right now need to see better shots of the which wires are going to the outside a/c unit. The white wire coming from the thermostat (the heat wire) is wire nutted to?

I'll try to separate the wiring better and take more pictures. Thanks so much for your effort. The digital photos are 5 megapixel and zooming in might help.

[integlikewhoa]

Yes, this is the case. However, the blue and white conductors are cross connected in the two cables.

Got it, I couldn't see that from the pictures. More pictures from this area with wires moved around a bit will help.

I'll try to separate the wiring better and take more pictures. Thanks so much for your effort. The digital photos are 5 megapixel and zooming in might help.

I did zoom in on them, the problem is more some wires covering or are in front of others hard to tell whats happening behind.

I'm still think we going to be good with the 5 wires, but we will have a to move the blue on the thermostat to the RC (which you can do now) and you should see the thermostat power up. After that if we need to make any changes it will be done in the air handler. So I would go ahead and finish the Thermostat and pop it on the wall after you move the blue O wire to the RC spot. 

[GoingGreen]

This photo should be a bit better. Let me know.

I am anxious to get the unit back in operation because the forecast is for several triple-digit days coming up soon. So far the weather has been on my side.

I will go ahead and remove the Braburn mounting plate, install the Trane mounting plate and connect the red, yellow and green wires since there seems no problem with these. Then when I get an answer back from you I can connect the white and blue. After that all should be good.

[GoingGreen]

Reviewing all the posts and pictures again I conclude it all comes down to where the blue conductor should be connected on the thermostat. Is that right?

[RichardTSchaefer]

He is hoping he can eliminate the white wire coming from the thermostat ... and then reuse it for another purpose.

The hope is that what white wire connects to at the air handler is ultimately the same spot as the blue wire ... As I mentioned earlier the blue wire controls the heat/cool switch over. And that in some units power on the blue wire indicates cooling, and in some cases power on the blue wire indicates heating.

@integlikewhoa
Has indicated in his case the power on the blue indicated heating. As a result the blue and white wire were virtually indicating the same thing at the same time.  (If he's wrong than eliminating the yellow wire may be an option, because that means the blue wire follows the same indication as the yellow wire).

I would verify which situation you are in. You need a volt meter ... all of the following is low voltage so it's safe to handle when the power is on. Need to identify the 24V common.  You will need this later anyway ...
Between the 24V common and the the red wire to the thermostat you should ALWAYS have 24volts.
With the thermostat OFF ... you should not have any power between the 24V common and any of the following thermostat wires:
     Yellow, Blue, White, Green
Now make the thermostat call for cooling ....  You should now have 24V between the 24V common and the following thermostat wires:
      Red (Always), Yellow (AC), Green (Fan). 
You should NOT have power between the 24V common and
      Blue(Heatpump SwitchOver) and White(Heat)

If you have power on the BLUE than we need an alternate strategy! If not you are good to proceed!
With that knowledge in the Air handler find the wires that connect to the blue wire that goes to the thermostat and the white wire that goes to the thermostat. Disconnect the wire that goes to the white wire to your thermostat and connect it to the same wire nut as the blue wire from the thermostat. (Now all of the blue wires should be connected together!).

Now the white wire from the Thermostat is disconnected (at the air handler). Install the trane thermostat using the same color codes. Except
on the Trane Thermostat change the white wire to the C connector. At the Air Handler you just need to connect the 24V Common wire on the transformer to this white wire on the thermostat.
You still have a 50/50 chance that this  will work properly without any other changes. At this point your Trane thermostat should be powered.
You need to make the thermostat call for AC ... Now is the Air HOT or COLD ? If it's HOT you need to reverse the polarity of the HeatPump switch over (which controls the blue wire). You need to follow the installers instructions for the Thermostat to do this.

[GoingGreen]

Ok, we are making progress. I have installed the Trane mounting bracket and will connect the yellow and green wires to their quick connect points. Power is off at the circuit breaker.

I cannot locate my voltage meter. Drat! It was a very cheap unit and could use a better one so I'll be off to Lowes this afternoon. When I get back home the saga can continue.

Thanks Richard. 

[integlikewhoa]

I'm assuming the one lower in the pic is the one going to the thermostat. The higher one is going outside to the a/c unit.

Yes, this is correct. 

GoingGreen,  Looking at your last diagram I'm thinking the above could be wrong. I see the common (24C) going from the air handler to the blue wire of #2 (lower) and I'm thinking the outside unit usually has a constant common running to it with the power or hot coming threw the thermostat to the a/c unit. 

So I'm thinking that #2 is going to the outside unit and #1 is the thermostat. If that's the case you don't have common on the blue wire going to the thermostat currently which means don't bother moving blue wire around just yet.

Can you make sure where #1 and #2 are going first.

Thanks for the help Richard. I'm looking for a bit more tho. White wire in the top left of the pic. It should be Heat, coming from thermostat (assuming #1 is the thermostat, see above) going to something in the air handler. But unsure why if there is no heat in the air handler and I don't understand that wire (yet) on the wiring diagram I posted earlier. Whats your take?

If #2 is the thermostat then its running from the air handler to the AC, but I understand that even less.

[GoingGreen]

integlikewhoa:

"Can you make sure where #1 and #2 are going first."

#1 is the cable to the thermostat, #2 is the cable to the outside unit. If you look close at the blue wire nut immediately above #2 you will see where blue and white are cross connected between the cables.

I got my new multimeter, but have not made all the measurements Richard asked for. Had an appointment today and other things slowing me down. It is late afternoon now and my concentration is flagging, so will rest and have supper then make some readings.

[integlikewhoa]

integlikewhoa:

"Can you make sure where #1 and #2 are going first."

#1 is the cable to the thermostat, #2 is the cable to the outside unit. If you look close at the blue wire nut immediately above #2 you will see where blue and white are cross connected between the cables.

I got my new multimeter, but have not made all the measurements Richard asked for. Had an appointment today and other things slowing me down. It is late afternoon now and my concentration is flagging, so will rest and have supper then make some readings.

Ok that's what I thought. So there is no 24C (2 blues twisted together in the bottom right) going to the thermostat. Eventually we will need to use one of the existing wires or a new wire to the 24C of the thermostat. Let me look over this a bit more.
And It would be nice to get a model number off the outside AC unit or even better a picture of how they have the wires in there. If not the testing of the wires as Richard suggested would also give us an Idea of whats going on.

[RichardTSchaefer]

If you are correct about the 24c being the blue wire ... then I had the two wires backwards.
With the thermostat removed (the wires can still be screwed to the connectors) See if you have 24Volts between what you have labeled
24C and 24V power.

If your labeling is correct so far ... than what you called unsure (white) is currently the heat ... That's the one we will re-use.

The wire nut that is not labeled with the White and Blue wires is the HeatPump Heat/Cool changeover.

==================================================================================================
Forget my previous comments ... they would instead be:
Connect the White wire on the unsure wire not, the one that goes to the molex connector,  connect that to the unlabeled wire nut ... what I called the HeatPump heat/cool crossover. Because that wire is for heat!, but it will get powered from Heat/cool crossover.

Connect the white wire from the thermostat to the 24V common. (Make sure your thermostat is removed  before you do this!!!!!)
Now move the white wire on the thermostat to C on the thermostat for Trane ... and the other wires using the same previous color coding.

NOTE: The 24V Common wire is the only one you can't make a mistake with ... It's the one that if connected wrong can cause a problem. So it's very important that we get that one right!  You can short all the other wires together accidentally and the most that will happen is the heat, cool, or fan will come on.