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-   -   Trane XR13 Contactor Bad? (http://www.diychatroom.com/f17/trane-xr13-contactor-bad-197668/)

sourkraus 03-11-2014 10:55 PM

Trane XR13 Contactor Bad?
 
I have a Trane XR13. The unit cooled back in November, but hasn't been run since. When I tried to turn the A/C on, the fan in the house blows, but no cold air. I've checked the breaker to the compressor and it is fine. I've opened the A/C unit and checked the load side of the contactor (c147094p05) and it returns 240v. If I put both probes on the non-load side, no reading. If I put one probe on a load terminal and then the other probe on any other terminal (non-load side or either 24v pole) I get a 120v reading. If I put either probe on either of the 24v poles I get no reading. Note I have a very rudimentary voltmeter that only reads 120/240. So, I'm not sure I would expect it to light up with only a 24v load.

Is this enough info to determine that the contactor is bad? Or could it be something else?

beenthere 03-12-2014 06:29 AM

If you don't have 24 volts coming to the contactors coil, the contactor won't close. need to see if you have 24 volts. And if not trace out why.

sourkraus 03-12-2014 08:11 AM

Thanks. Makes sense. Sounds like I need to pick up a better voltmeter so I can check for the 24v signal.

Related question. I recently changed out the thermostat. The installation "seemed" to go pretty easy, but in retrospect I've yet to successfully run the A/C with the new thermostat. I'm wondering if the signal is even getting sent to the A/C unit. Is there a way to validate the signal from the thermostat is making it to the Integrated Furnace Controller?

yuri 03-12-2014 10:03 AM

You press in the door switch and tape it closed and then check from Y to C on the controller when it is set to cool and turned down to call for cooling. Sears has good reasonable meters. Buy one that can check capacitance and microamps as you may need that later for the furnace and AC. Should list that in the features.

sourkraus 03-12-2014 10:19 AM

Thanks Yuri. Can you further explain what you mean by "check from Y to C on the controller when it is set to cool and turned down to call for cooling"?

Right now, I have a each of the five colored wires mapped between thermostat to IFC board. Y to Y, C to C, etc.

yuri 03-12-2014 11:03 AM

you should get 24 volts when calling for cooling.

you can also use the ohmmeter continuity check of the meter to check if you have a circuit thru the thermostat and wires. need to remove the wires from the controller and connect to them your meter with alligator clips not your fingers or the meter will read continuity thru your body. Radio Shack should have meters and clips too.

sourkraus 03-12-2014 09:13 PM

OK...here's an update. I put a voltmeter on R and Y and it was pulling 28.8 which "I think" indicates that the thermostat is sending a Cooling call. I went outside to the A/C unit and I pulled 240v on the load side of the contactor. When I tested the 24v calling posts, I got a near zero reading. If I manually push the contactor plunger down, the A/C unit fires right up. So, I think the thermostat is working and the A/C is working. Which leads me to believe there is an issue in the control board or in the manner which it is wired.

This is a good transition for some additional information I should have previously shared. I recently changed thermometers and this was right around the time when things stopped working. My prior thermometer was a battery powered system. My new thermometer has WiFi so requires a 5th wire for power. Here are the old and new wiring configs:

OLD CONFIG (thermostat - IFC):
Y - C
G - G
R - R (note the R-Rc jumper is in place)
W - W


NEW CONFIG (thermostat - IFC)
Y - Y
G - G
R - R (note the R-Rc jumper is in place)
W - W
C - C

Anything wrong with the new wiring configuration?

ben's plumbing 03-12-2014 09:23 PM

it sounds like you are not getting 24 volts to contactor relay...yuri wanted you to tape in door switch on furnace set thermostat to cool.. go down to furnace where stat wires connect to control board.. .measure voltage from y terminal to c common....should read 24 volts...not r to y ...ben sr... picture of you furnace with bottom door off and close up of board...would help

sourkraus 03-12-2014 09:38 PM

Agree on the lack of 24v to contactor.

With the system in Cool, I pull 27.07v from Y-C on the control board.

ben's plumbing 03-12-2014 09:40 PM

Quote:

Originally Posted by sourkraus (Post 1321221)
Agree on the lack of 24v to contactor.

With the system in Cool, I pull 27.07v from Y-C on the control board.

is the contactor control wire hooked also to the y and c terminal on control board..ben sr

sourkraus 03-12-2014 09:44 PM

1 Attachment(s)
I don't think so, but honestly not 100% sure how to validate. The Y and C terminal are only single tapped (with the thermostat wiring) so I'm guessing not.

ben's plumbing 03-12-2014 09:57 PM

1 Attachment(s)
I dont see where contactor control wires hook on to board....trace line set to see if you can find 18 guage wire ....also look at this ...not an artist..:laughing: ben sr

ben's plumbing 03-12-2014 09:59 PM

did you run new stat wire from furnace to new stat because you needed 5 wires instead of 4..if so you removed control wire to a/c and did not put it back?????? ben sr

sourkraus 03-12-2014 10:01 PM

I noted the color of the 18 gauge wire in the A/C compressor that was connected to the contactor and I cannot see where it is coming into the furnace. I understand that it is possible that the wire was changed/spliced somewhere in the run.

Is there ever another way the 24v line is connected?

As an additional data point, the system does have a built in humidifier.

This schematic (page 4) echos your artistic rendering. ;)
http://www.emersonclimate.com/Docume.../0037-6270.pdf

ben's plumbing 03-12-2014 10:05 PM

Quote:

Originally Posted by sourkraus (Post 1321231)
I noted the color of the 18 gauge wire in the A/C compressor that was connected to the contactor and I cannot see where it is coming into the furnace. I understand that it is possible that the wire was changed/spliced somewhere in the run.

Is there ever another way the 24v line is connected?

As an additional data point, the system does have a built in humidifier.

This schematic (page 4) echos your artistic rendering. ;)
http://www.emersonclimate.com/Docume.../0037-6270.pdf

where the line set and electrial suppy come into the compressor there should also be a small 2 conductor wire ..see if you can see that and trace it backwards...ben sr


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