I Killed My Trane

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  #1  
Old 10-09-07, 02:04 PM
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Question I Killed My Trane

Hi everyone,
need some help with my Trane XE 1000. Simple task of replacing a 1987 Trane Thermostat has turned into 3 days with no A/C in Florida. I hooked up a new Honeywell digital thermostat and it worked fine. I had to disconnect it a couple days later to hang the drywall and when I reconnected the thermostat I got nothing. I reconnected the old Trane thermostat and got nothing. I found the fuse on the air handler power supply blown, replaced it and now the air handler works fine but the heat pump still wont run. I've matched up the wiring between the air handler and the thermostat, all connections are correct. Is there a reset button or a fuse inside the heat pump I need to check??? The contractor I called said he thinks it the transformer inside the air handler but I can hear it humming just like before.
 
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Old 10-09-07, 02:45 PM
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if your air handler works, I'd check the low voltage wire on the air handler itself.

before you check, make sure your breaker/fuse are good both in the main panel in your home, and next to the unit!

If wires are in place on the board as it should be, then I'd check your low voltage reading outdoors.

Take a meter to check for voltage going to the contactor.
 
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Old 10-09-07, 02:50 PM
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I'll check for voltage outside, thanks. I was going through the schematic for the air handler and dont see anything sending power or a signal to the heat pump. Does the t-stat control the heat pump (on-off)??? Thanks for the help Jay.

Eric
 
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Old 10-09-07, 03:02 PM
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Most wire will go to the air handler from the t-stat, then from air handler to the outdoor unit.

Check the Y.

What model of t-stat did you get?
 
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Old 10-09-07, 03:07 PM
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Honeywell RTH 3100C. My T-stat cable is a rats nest between the air handler & heat pump, not sure who installed it but it needs to be replaced after I get the a/c working again. My XE 1000 is a 95' model and the air handler is an
87' Trane.
 
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Old 10-09-07, 03:31 PM
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Pretty basic stat there.. I looked it up, and I see it didn't ask for any advance settings like "type of equipment", so nothing is set up wrong since it didn't give us that options.
 
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Old 10-09-07, 04:16 PM
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Yeah it is, I dont want anything special.

Ok, I checked the heat pump. I've got 24V coming in on 2 wires. I pressed in the contact on the contactor and everything came on great (I've got a stick holding it in for now too cool the house down). I've got a yellow and blue wire going to the contactor from the t-stat cable that I think should energize the switch that arent getting power. Everything else has power and I've got a red LED on the circuit board thats lit up.
 
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Old 10-09-07, 04:24 PM
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Wink

Might check on the 24V common this has to go to the outside unit. Then the tstat will send Y for compressor and that blue dont it come off O. That is the 4 way valve that will let you have the cool or the heat from the pump.
 
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Old 10-09-07, 04:32 PM
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(I've got a stick holding it in for now too cool the house down).
Now thats a scary statement YIKES
If you have verified that you have 24 volts at the contactor and it is not pulling in you will need to replace the contactor.
Dude I know its hot down there but if your safety systems cannot shut the unit down because of a stick holding in the contactor you stand a good chance of really KILLING the unit. Voltage can be a bit tricky to check exactly how are you placing your test leads to get 24 volts and are we doing this when the t-stat is calling for cool and then when it is in the off position to double check our reading?
 
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Old 10-10-07, 03:17 PM
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Yeah I know the stick in the contactor's not a good thing too do, I only let it run for about 10 minutes. But on a good noted note I guess that fixed the problem. Got up this morning and turn the t-stat to cool just because and it came right on.....been running all day no problem.
Just want to thank everyone for their time and help. I guess the gremlin's got bored and left or something.

Eric
 
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Old 10-10-07, 04:27 PM
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The Contactor maybe was dirty or had a spider web.. Make sure that area is clear of spider webs, and what not.
 
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Old 10-11-07, 05:38 AM
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Like already mentioned, if you have 24 volts to the contactor and it's not pulling in, you likely have a bad contactor. Sometimes the mechanical parts will bind or the coil has a few shorted windings. This will not allow it to pull in. I have also seen shorted windings cause the transformer to burn out. So it may be best to just replace it now.

As always, check all connections carefully.
 
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