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Old 03-09-2010, 08:40 PM   #1
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Trane Heat Pump Problems (heat instead of cool)


I have a Trane XE1000 TWR036C100A Heat Pump from about 1998 with electric aux. heat. The blower motor was replaced in the summer of 2009 and I replaced the thermostat with an electronic one in the fall of 2009. Receintly the compressor fan was replaced and a new capacitor was installed (old split cap still connected to compressor). That information was mainly for background. When I turned the A/C on it ran for a long time and increased the house temperature to 80+ degrees (no cooling). I opened the outside unit and noticed a brown wire from T1 on the defrost control board (CNT1923) was not connected. It was hanging down by the other low voltage connectors coming from the inside unit (5 connections matching wire color - Red, Yellow, Black, Blue, Orange - White, Green, and Brown not used) but not obvious where it should go - possibly knocked loose when the pannel was opened or motor replaced? I figured it should be connected to one of the other low voltage connections since nothing else is near by (maybe orange wire for cool changeover or blue for common). Where should the T1 wire from the control board be connected to if the low voltage brown T wire not used from the thermostat. I was thinking the reversing valve was not not engaging to enable cooling and it is possibly related to the unconnected wire. I have pictures and all part numbers if needed.

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Old 03-10-2010, 09:02 AM   #2
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Trane Heat Pump Problems (heat instead of cool)


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Originally Posted by leesimmonds View Post
I have a Trane XE1000 TWR036C100A Heat Pump from about 1998 with electric aux. heat. The blower motor was replaced in the summer of 2009 and I replaced the thermostat with an electronic one in the fall of 2009. Receintly the compressor fan was replaced and a new capacitor was installed (old split cap still connected to compressor). That information was mainly for background. When I turned the A/C on it ran for a long time and increased the house temperature to 80+ degrees (no cooling). I opened the outside unit and noticed a brown wire from T1 on the defrost control board (CNT1923) was not connected. It was hanging down by the other low voltage connectors coming from the inside unit (5 connections matching wire color - Red, Yellow, Black, Blue, Orange - White, Green, and Brown not used) but not obvious where it should go - possibly knocked loose when the pannel was opened or motor replaced? I figured it should be connected to one of the other low voltage connections since nothing else is near by (maybe orange wire for cool changeover or blue for common). Where should the T1 wire from the control board be connected to if the low voltage brown T wire not used from the thermostat. I was thinking the reversing valve was not not engaging to enable cooling and it is possibly related to the unconnected wire. I have pictures and all part numbers if needed.

Leave the T wire disconnected and taped off. Did you test the unit operation when you replaced the thermostat? Is this the first time you are using your a/c, since you installed the new thermostat last fall? If so, I would double check your wiring and make sure you bought the correct thermostat.

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Old 03-10-2010, 05:04 PM   #3
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Trane Heat Pump Problems (heat instead of cool)


I agree with Pomelo, the most likely cause is a misconfigured, incorrectly wired, or incorrect stat.

What stat do you now have installed?


If you have had cooling since the installation of your new stat...
Do you have 24VAC between R and O with a cooling demand?
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Old 03-10-2010, 06:30 PM   #4
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Trane Heat Pump Problems (heat instead of cool)


The A/C had been working but it has been a colder than average winter in Austin so it hasn't been on in awhile. The compresser and fan come on but just blow hot air. I will need to check the voltage tomorrow. It is strange that the brown wire is hanging down near the other wires with no connector and isn't taped off and obviously was stripped for connection to something. The other unused wires are not stripped. Any other suggestions since my responses may be time delayed. I can attach pictures if needed. Is the T1 brown wire not used in my configuration outside (I know the inside wire isn't connected to anything but figured the outside one might be connected internally). Thanks for the help.
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Old 03-10-2010, 06:36 PM   #5
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Trane Heat Pump Problems (heat instead of cool)


I forget the model of the thermostat but I can look it up when I get home. It is a new white rodgers blue touch screen programmable that handles heat pumps with emergency/aux heat connections.
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Trane Heat Pump Problems (heat instead of cool)-ac.jpg   Trane Heat Pump Problems (heat instead of cool)-wire.jpg  

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Old 03-10-2010, 08:03 PM   #6
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Trane Heat Pump Problems (heat instead of cool)


Forget about the tan wire; it has nothing to do with your problem. Just tape it off. If you have a meter, it would be easier to troubleshoot.

You can try and diagnose it without one.

First, you need to see if it actually is in the heat cycle. Turn the t-stat to cool and lower the set point. Feel the larger copper pipe exiting the unit (where the service valves are). Is it hot?

-If yes, then it is in the heat cycle.

Check the coil on the reversing valve. It should be making a humming noise. You can remove the coil from the valve. You should feel resistance when pulling it off the solenoid. Stick a screw driver inside the coil. You should feel the magnetic field.

Your reversing valve could be stuck, but I would look for other things first. I would look at your old paper work to see if you purchased a heat pump stat.
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Old 03-10-2010, 11:17 PM   #7
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Trane Heat Pump Problems (heat instead of cool)


The factory setting is probably not heat pump on your new stat.
It should be HP1 (depending on your model number).
Post your stat model number if you cannot locate the manual and verify the configuration setting.

That tan wire was for for your old baystat and is not required, or supported, by your new stat.

This is a 1F95-1271 example. Color codes vary, and you will not use the B, Y2, or L terminals.

Last edited by Houston204; 03-10-2010 at 11:21 PM.
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Old 03-12-2010, 01:10 AM   #8
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Trane Heat Pump Problems (heat instead of cool)


I'm on kind of a strange schedule so my replys will be a little delayed. Thanks fot the info so far - I appreciate it. I am an Engineer so I feel pretty comfortable working with meters and electricity. I'm pretty sure the thermostat is programmed properly (it is a White Rodgers 1F95-1277 and set for HP and Electric - I can send other settings if you need them). I tested the outside unit today (it was about 70 outside) and in Cool mode - the reversing valve was humming, the fan was blowing cool air up and out, the large copper tubing was hot and the small one was slightly warm, and the air inside was hot. I measured 24+ volts on the Red, Orange, and Yellow wires which you would expect for Cool (Orange - Yellow for the Compressor). I also measured 24+ volts across the reversing valve. I am pretty sure the A/C worked last fall when it was warmer but it hasn't been on all winter. The outside fan was just changed 2 weeks ago so I assume it happened at that time but I can't prove that. Is there any way swapping out the fan with the same model and adding a new capacitor for the fan (changed from 5 to 7.5 so the new one was jumpered from the old split cap that is still connected to the compresser from the common and the two fan wires were connected to the new cap)? Any other tests or info would be greatly appreciated and hopefully this weekend I can work on it.
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Old 03-12-2010, 07:20 AM   #9
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Trane Heat Pump Problems (heat instead of cool)


Large copper line hot with 24 volts to the reversing valve means the reversing valve is stuck in the heating position. Repairs are going to be expensive, probably 25-30% of the cost of replacing the whole unit.
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Old 03-12-2010, 10:40 AM   #10
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Trane Heat Pump Problems (heat instead of cool)


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Originally Posted by leesimmonds View Post
I'm on kind of a strange schedule so my replys will be a little delayed. Thanks fot the info so far - I appreciate it. I am an Engineer so I feel pretty comfortable working with meters and electricity. I'm pretty sure the thermostat is programmed properly (it is a White Rodgers 1F95-1277 and set for HP and Electric - I can send other settings if you need them). I tested the outside unit today (it was about 70 outside) and in Cool mode - the reversing valve was humming, the fan was blowing cool air up and out, the large copper tubing was hot and the small one was slightly warm, and the air inside was hot. I measured 24+ volts on the Red, Orange, and Yellow wires which you would expect for Cool (Orange - Yellow for the Compressor). I also measured 24+ volts across the reversing valve. I am pretty sure the A/C worked last fall when it was warmer but it hasn't been on all winter. The outside fan was just changed 2 weeks ago so I assume it happened at that time but I can't prove that. Is there any way swapping out the fan with the same model and adding a new capacitor for the fan (changed from 5 to 7.5 so the new one was jumpered from the old split cap that is still connected to the compresser from the common and the two fan wires were connected to the new cap)? Any other tests or info would be greatly appreciated and hopefully this weekend I can work on it.


Did you try to remove the coil and try my test procedure? If you can feel the magnetic field, your reversing valve is stuck. You can try and break it free, but it will more than likely get stuck again. Disconnect one of the leads off of the coil then reconnect it. Do this multiple times with the unit running. You should hear it engage each time. Get a rubber mallet and tap on the reversing valve body. Do not hit it with excessive force. You will notice when it changes over. It makes a distinctive sound. Let it run in the cooling mode for a few minutes then switch it back to heat by removing the leads. Reversing valves are more difficult than compressor change outs, so you will be paying a lot in labor. I have only changed them under warranty. Usually, a person will opt for a new unit, if it is no longer under warranty.
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Old 03-17-2010, 06:30 PM   #11
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Trane Heat Pump Problems (heat instead of cool)


Sorry for the late response. I did test the coil and it seems to be working. It was humming and I could disconnect a lead and reconnect it and it would click. I also tested the screwdriver in the coil and there was a magnetic field. But it still seems to be stuck. I will have someone come out and get a quote for how much it will be to replace the valve unless someone else has any suggestions. Thanks again for the information.
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Old 03-17-2010, 06:32 PM   #12
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Trane Heat Pump Problems (heat instead of cool)


Is it possible the coil isn't strong enough to cause the reversing valve to change? Is there a better way to prove the reversing valve is bad.
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Old 03-22-2011, 04:23 AM   #13
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Trane Heat Pump Problems (heat instead of cool)


I had the same problem with my trane unit. model# wcy036f100ac. The trick to solving this problem for me was to make sure the settings were correct on my new thermostat. I just had to set heat pump mode and ob energized to cool and my problem was solved. The trane unit I have doesn't work correctly with any other settings.

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