Original message
| ZackyZ
 |  "AC Trane compressor not working, help!"
, posted Thu 15 May 15:23  
Hi, I'm an amature fixing AC units, this is my firt attempt to fix one. I have a Trane XE 1200, the blower on my ac unit quit working but the compressor used to work fine...I called the AC guy and he wanted to charge me $500 to replace the circuit board...hours later the compressor stopped working too. I replaced the circuit board myself for $100, now the blower works fine but the compressor still doesn't work. I checked the cicuit brake and all is good...please help me troubleshoot the compressor.
Thanks!
Zack
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Replies:
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| theduke03
| "Re(1):AC Trane compressor not working, help!" , posted Thu 15 May 17:41
Did you leave the compressor running when blower stopped running? That would be bad. Do you have a meter? If so set stat to call for ac and check at outdoor unit for 24v between Y and C, usually they're the only two low voltage wires.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | zackyz
| "Re(2):AC Trane compressor not working, help!" , posted Thu 15 May 18:17
Yes I left the compressor running with the blower off...didn't know any better. Yes there are 24V between Y and C. I also checked the power going to the contactor from the power supply and is very low 200mV but the AC fuses are good I think, I checked them with an Ohmeter and they have continuity....Thanks in advance for your help!
Thanks!
Zack
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| | theduke03
| "Re(3):AC Trane compressor not working, help!" , posted Thu 15 May 18:28
200 mv = 1/5 of 1 volt. which = 0 volts. You may want to check that breaker again and check that the disconnect switch is on or plugged in correctly. Many homeowners can not identify a tripped breaker if it had a sign on it that said tripped! If breaker is tripped you have other problems. Let us know what you find.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | zackyz
| "Re(4):AC Trane compressor not working, help!" , posted Thu 15 May 19:30
Hi, I'm attaching a couple of pictures to help me explain...
I have two units side by side, I checked the power to the fuse boxes and one reads 240V the other 0V, at did the reading at the power input of the fuse so this verifies there is no power coming from the fuse box. I checked the circuit breaker box and all breakers are fine (just in case I toggled them off/on). I don't see any other circuit breaker box that would give power to the fuse box...thanks again for the help so far.
http://farm4.static.flickr.com/3257/2495183621_903306487c_o.jpg
http://farm4.static.flickr.com/3278/2495183575_1ae9e4dc98_o.jpg
Thanks!
Zack
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| | theduke03
| "Re(5):AC Trane compressor not working, help!" , posted Thu 15 May 19:49:
I am a bit confused. When you check these voltages check from L1 to L2. Not from line to ground. Now check for 230 between the 2 fuses on both sides. If what you are saying is that the breaker is on and no power coming from fuses would suggest a blown fuse but that would not explain the continuity that you reported so something is not accurate..
To post pictures upload them to photobucket.com and click on img code to copy it. Then paste in your message.
"My dad was the most feared furnace fighter in Northern Indiana."
[this message was edited by theduke03 on Thu 15 May 19:58] |
| | zackyz
| "Re(6):AC Trane compressor not working, help!" , posted Thu 15 May 20:41
Ok, I was calling the "power disconnect box" next to the condenser, a fuse box. Finally figured out I had two circuit breaker boxes, one outside the house that controlled the "power disconnect box", the breaker was tripped. I turned on the AC and put the fuses in the disconnect box and the fuses blew out. I guess I have a short in the unit, any ideas?
Thanks!
Zack
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| | theduke03
| "Re(7):AC Trane compressor not working, help!" , posted Thu 15 May 20:51
You most likely have a grounded compressor or mouse chewed wires. Shut power off to inside and outside units. Visually inspect wires for damage. Disconnect 3 compressor wires(2 from contactor and 1 from capacitor). leave the other end connected to compressor and check ohms between each wire and ground.
Open or infinate = good so far
0 or measurable ohms= compressor shorted and must be replaced.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | zackyz
| "Re(8):AC Trane compressor not working, help!" , posted Thu 15 May 22:49
Ok, I think so far so good, I checked the wires coming from the condenser to ground with ohmeter at continuity and they were all at infinity, checked again with ohmenter but no continuity beep and I got large numbers like 4M Ohms, this seems to be an open circut. I'm attaching a picture...wires seem to be ok, no mouse chews...now what would be the next step?
http://i303.photobucket.com/albums/nn153/zackyz/Condeser_Wires.jpg
Thanks!
Zack
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| | Houston204
| "Re(9):AC Trane compressor not working, help!" , posted Fri 16 May 23:56
"Tip of the Day" Remember to remove power first.
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| | learner
| "Re(9):AC Trane compressor not working, help!" , posted Thu 15 May 23:09
Hi,
Turn of breaker and measure with meter for continuity between two hot, between either hot and ground wire at unit side. What do you see? Power is going to fan motor as well as compressor. Another way to figure out is disconnecting fan motor or compressor at a time and apply power.
Good luck.
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| | tinmantu
| "Re(8):AC Trane compressor not working, help!" , posted Thu 15 May 21:20
Check to see if you have crank case heater....wish I had a buck for every one that shorted out.
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| | theduke03
| "Re(9):AC Trane compressor not working, help!" , posted Fri 16 May 07:27
I can tell from your picture that you do not have a crankcase heater. Will compressor run if you reset breaker? The compressor may have seized from running like it did. At this point you either have a bad capacitor or a locked rotor on the compressor. I must go to work now but hopefully one of the other fine fellas on this site will tell you how to test these things, otherwise I'll reply later.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | zackyz
| "Re(10):AC Trane compressor not working, help!" , posted Fri 16 May 13:38
Hi, tested the compressor with the condenser wires unplugged and the motor ran fine. Plugged the conpressor wires back and it tripped the breakers again.
I have two Trane XE1200 units side by side, I took the capacitor from the working unit and tried it in the bad one and it keeps tripping the breakers. I also tried the capacitor from the bad unit to the good unit and the capacitor works, so capacitors are good....how do I test the condenser?
Thanks!
Zack
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| | theduke03
| "Re(2):Re(10):AC Trane compressor not working," , posted Fri 16 May 16:06
the condenser is not an electrical devise so it needs no testing. It is now obvious that the compressor is causing the trip. If your ohm testing was accurate then compressor is not grounded(good), however compressor is locked(a motor that cannot spin/stuck) and this is the problem. I recommend adding a hard start kit to it as this is now the only hope of saving the compressor. You can find one at any hvac distributor. It looks like this:
Simply attach one wire to common terminal on capacitor(c), connect the other wire to compressor terminal on capacitor(H or Herm). Turn power on and cross your fingers. If this doesn't work you will need a new compressor or a whole new unit.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | zackyz
| "Re(3):Re(10):AC Trane compressor not working," , posted Fri 16 May 17:41
I tested the resistance from the compressor wires, red to black and got about 1.5 Ohms (wires from compressor to contactor), from red to orange (Herm/capacitor) 2.5 Ohms, and from black to orange 1.5 Ohms.
I will try as you suggested with a hard start kit, and cross my fingers, I will let you know as I order the part online and should get it early next week.
Thank you again, I really appreciate all your help! I will post next week with my final attempt.
Thanks!
Zack
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| | theduke03
| "Re(4):Re(10):AC Trane compressor not working," , posted Sat 17 May 13:01:
While you're at it, I have 3 observations you may want to address.
1 is the ohm readings between compressor wires. Could you repeat that test and make sure ohmmeter is on lowest scale(if adjustable) and post results.
2 is that the terminals on your capacitor look a bit crusty. I would clean them up with a wirebrush,steel wool, or whatever have you before putting it all back together.
3 is the contactor looks like it got hit with a baseball bat. Not saying it's causing an issue, but worth a closer look.
Zack, as for your previous posts about ignorance and amateurism, I think you're doing great. If hard start works then you will have saved a couple hundred on the service call.
"My dad was the most feared furnace fighter in Northern Indiana."
[this message was edited by theduke03 on Mon 19 May 21:36] |
| | zackyz
| "Re(9):AC Trane compressor not working, help!" , posted Thu 15 May 22:59
Sorry about the ignorance but I don't know much about AC units...how do I check if the crankcase heater is shorted? Where is it located by the compressor outside unit or by the furnace housing?
Thanks!
Zack
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| | zackyz
| "Re(10):AC Trane compressor not working, help!" , posted Tue 20 May 18:08
Hi Duke,
I have bad news/good news, bad news is that the the compressor finally shorted to ground, it happened when a friend came to look at it, I din't even get the chance to try the start up kit. Good news is that a tech came by and told me the unit was still under warranty (didn't know as I had bought the house about a year ago), so they will replace it for free.
Again thanks so much for all you help, I learned a lot, main lesson is not to let the condenser run when the blower gives up ;-)
Thanks!
Zack
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