What did I break?

Problems related to residential installations.

What did I break?

Postby Macnbaish » Sat Feb 19, 2011 10:32 am

OK, I'll try to keep this as short as possible. I wanted to upgrade my "dumb" thermostat to a programmable one. I have a heat pump unit with auxiliary\emergency elements. The wiring of the new thermostat wasn't exactly clear, and I may have an incompatible one. I'm not sure. I was an idiot and wired it up anyway and turned it on. Nothing happened. No fan, nothing. So I took it back out and reinstalled the original thermostat. Now the blower comes on, and the auxiliary elements will kick in, but the outside compressor unit will not start up. I checked the breakers at my breaker box and all are good there. I checked the kill switch at the wall box by the compressor. It does not have fuses, so that can't be the issue. I took the service panel off of the compressor unit in case there is anything to reset in there. It is a Trane XR13 unit (model WR3030A1000AA). I didn't see anything to reset, but I did notice that there was a circuit board, with a green LCD. The LCD is flashing steadily, but slowly. I also noticed that there was some electrical noise, it appeared to be coming from the capacitor. It was a quiet hum with occasional soft popping sounds.

So, any ideas what I broke? Is there a simple way to test and find out? I am fairly competent with a multimeter.
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- What did I break?

Postby Macnbaish » Sun Feb 20, 2011 12:02 am

Got home tonight and checked the light again... this time the LED was flashing twice every cycle... so that's different. I hope to gather the readings you mentioned first thing tomorrow.
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Postby Macnbaish » Sun Feb 20, 2011 9:23 am

OK, here's what I found, please forgive my ignorance. When you said check at the control, My best guess of that was this thing, the defrost -

*-*://macnbaish.sexypenguins.com/hvac1.*/-*

My color options there are BR, RD, YL, WH\RD, BK, OR, BL, BL, YL, OR. I thought maybe you meant Red and Yellow for R and Y, but I don't know what "C" would be. Sorry about that.

Secondly, the -

*-*://macnbaish.sexypenguins.com/hvac2.*/-*

Basically on this guy everywhere I measured I got 0 volts. I measured across on both sides, then L1-L2, and T1-T2 like you specified. No voltage anywhere which kind of surprised me. Based on your instructions, I measured between the contact on the contactor, not to one of the contactor contacts to ground. Is that what you meant? Sorry if I'm being dense.
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Postby nomadpeo » Mon Feb 21, 2011 12:02 am

'r', 'y' and 'c' refer to terminals of the wires from the house. 'r' and 'y' should each read 24 vac to 'c'. you may have reconnected something back differently than it was before. what was the reason for the thermostat change. i agree with dilkey. even with knowldedge of how to use the meter, if you do not know what signals represent or where to read them, you may be better off to get it checked. heat pumps can be complicated for those with experience. it's not likely we would be able to guide you through a checkout. if you were having problems that prompted you to replace the thermostat to start with, there are too many variables and possibilities.

by the way, if you have a flashing code, the meaning of the code may be posted on the inside panel.
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Postby Macnbaish » Mon Feb 21, 2011 1:15 am

OK, I have more information tonight, but before I get into that, I'm going to start this story from the beginning.

This house is barely 5 years old, so it's the original system that was put in. It's a "cookie cutter" type of subdivision. I do not own the home, I started a lease this past August. I asked the Landlord when I moved in if he would mind if I installed a programmable thermostat to help on the utility bills. He said that was fine.

Fast forward to late December. It was the first really cold snap of the year, and the heat pump was not keeping up. It was running 24/7, and overnight it would get several degrees below the set point. One morning it got especially cold, and was ten degrees below set point. At this point I couldn't dismiss the problem any more. I called the landlord. He sent out a local HVAC contractor to take a look. I had done my research online and my amateur opinion is that my backup elements weren't engaging, since the compressor was running 24/7 and just couldn't maintain temp. The HVAC guy went straight to the heat exchanger to look at the wiring. He said he found that the elements had not been wired into the "Normal" cycle, and had only been connected to the "Emergency Heat" setting. So he took one of the white wires there that had been just capped off to nothing, and bundled it in with a bunch of other white wires that were already bundled together. The output temperature increased to where he expected it to be, so he considered the problem fixed and left.

At this point the heat pump was able to keep the temperature at the set point, but my electric bill continued to be sky high. Granted, it's been a very cold winter, but as things have warmed up I started noticing that it was kicking over to auxiliary heating, even when it was in the 40s outside. My online research indicated that auxiliary heating should only be needed when it was 20 degrees or colder outside. I had been putting off getting the programmable thermostat, but two months of $200 plus heating bills prodded me into biting the bullet and doing it. I thought maybe the existing thermostat was faulty and was kicking on the aux elements when it shouldn't. So that's how I arrived at last weekend. You've heard that story.

So today, I spoke with my cousin, who is a certified HVAC person. I wouldn't consider him an "expert," but he can troubleshoot and fix most common issues; he is the maintenance lead at an apartment complex and does most of the HVAC work there. He said he could come over tonight and at least take a look. He took a look at everything in the heat exchanger, and out at the compressor, but he couldn't tell what was wrong. He called an expert he knows to get his opinion, and he immediately suggested the problem was probably at the thermostat (likely because I had recently been fiddling with it. ). We read off the wires to him, this is what they -

Green - G
Blue - C
Red - R
Yellow - W1 jumpered with Y
Black - W2
White - E
Orange - O

Now I'm 99% sure that is what they were before I started messing with the thermostat. I was careful to label each wire so I could get them back just like they were. Anyway, HVAC expert friend said that the Black and White wires were backwards, so we should switch them. So now it is wired like -

Green - G
Blue - C
Red - R
Yellow - W1 jumpered with Y
Black - E
White - W2
Orange - O

After turning the system back on, we still had no compressor. I was starting to think the worst, so I had resigned myself to calling the landlord and saying that something was wrong and needed to be checked out. Tidying things up, I put the access cover on the outside compressor unit, and gave it a smack with my palm to move it into place... and the compressor and fan kicked on.

So, now the compressor is kicking on on its own... and it is putting out heat. But I still have one final concern. I've noticed that now, every five minutes or so, it's kicking on the auxiliary elements. Then it seems to turn them off for a few minutes, then back on. The temperature is at the set point, so it's not having to do catch-up. It is 60 degrees outside. Is that normal???? I think I'm going to start having nightmares. Thanks in advance for any insights.
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Postby nomadpeo » Mon Feb 21, 2011 9:47 pm

the jolt could indicate a contactor problem or a wire connection problem. the fact that aux heat is cycling with 60 outside could indicate a problem with the heatpump. in other words, if the heat pump is not performing for some reason, the heat strips could be carrying all the load. again, variables. clearly, something is/was hanging up. an intermitent problem like that will go solid eventually. had signals been tested before the jolt, it could have been narrowed down. it's difficult to say whether the hanging control and the performance problem are the same problem, but more than one probem with the same unit is less isolated than you might think. i know it's frustrating, but if you are determined to figure out some things on your own, you will need take some progressive readings and observations. you might start by setting the thermostat one degree above room temperature and see what's running. document the sequence of what runs and while the compressor is running, note the feel of the freon lines and air coming out of the heat pump. although you can't take pressure readings, that info will be helpful. if you catch the compressor not running, break out your meter and test those low voltage signals outside. again, the termination points of the wires. r to c and y to c. good luck.
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Postby Macnbaish » Wed Feb 23, 2011 1:41 pm

After waking up the following morning, the compressor was once again not running. I called the landlord and an HVAC repairman was at my home yesterday afternoon. He opened the compressor unit and found that one of the 220V legs had been wired poorly, and the wire had completely fallen out of the cap. It was kind of hidden behind a bundle of wires, and it was dark when I and my cousin were looking, so that's why we hadn't noticed. After fixing that connection, the compressor kicked right on. He also took the time to test the refrigerant levels and said that those looked good. I also had him take a look at the thermostat wiring and confirm that all is well there. So luckily, it was not my fault.

Now I'm noticing just how finicky my (old) thermostat is. If the room drops to two degrees below set point, even for an instant, it kicks on the Aux elements and leaves them on all the way until the set point is reached. This morning for instance, I had the thermostat set at 69 all night. I got up and set the thermostat to 70 for the day. Just after I set that, as I was still standing there, the temp dropped to 68, And so of course the Aux elements were immediately kicked on. I went ahead and got ready for work, and checked as I left. The temp was up to 70, but the aux elements were still on. Grrrrrr.

So I'll be replacing it with a programmable ASAP. The correct one this time.

Oh and I now have a Lux TX9000TS that I can't return, if somebody is interested in it...

Thanks to everybody for their comments and suggestions, I appreciate it! I've learned a lot.
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