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airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 7745
Experience:  Furnace, A/C and heat pump specialist.
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JA: Thanks. Can you give me any more details

Customer Question

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JA: Thanks. Can you give me any more details about your issue?
Customer: I have a trane Xe 80 furnace and all of sudden the heat is not firing. the Tstat clicks on but not heat. The furnace works because the air and the fan go on I am getting 3 LED flashes in the little view finder
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Submitted: 7 months ago.
Category: HVAC
Expert:  airheatman replied 7 months ago.
The 3 flash code is a pressure switch issue.Does the small vent motor on furnace come on when you call for heat?
Customer: replied 7 months ago.
No. Nothing
Expert:  airheatman replied 7 months ago.
OK that motor must come on to pull a vacuum on pressure switch before anything else can happen.Our first step is to determine if we are getting voltage to that small motor.Do you have a volt meter?We would need a meter to troubleshoot. You can get an inexpensive one at Walmart for about 15 bucks if you would like to troubleshoot and I would be happy to guide you.http://www.walmart.com/ip/Innova-3300-Equus-3300-Hands-free-Digital-Multimeter/14644665
Customer: replied 7 months ago.
Yes. I have a volt meter
Expert:  airheatman replied 7 months ago.
OK do you see where the two wires connect to inducer fan motor?Turn power off to reset control board.Then power back on and We will turn thermostat to call for heat and see if we get power to the small motor.
Customer: replied 7 months ago.
I have no idea what the inducer is.
Expert:  airheatman replied 7 months ago.
It is the small vent motor were the pipe connects to furnace.
Customer: replied 7 months ago.
I am assuming it is behind the top panel
Expert:  airheatman replied 7 months ago.
Yes, remove top panel and locate the black and white wire where they connect to the vent inducer and that is where we want to check voltage on call for heat
Customer: replied 7 months ago.
I cannot get to the leads on the wires
Expert:  airheatman replied 7 months ago.
Do they have a plastic plug?
Customer: replied 7 months ago.
Yes
Expert:  airheatman replied 7 months ago.
Disconnect from motor and stick leads in plug coming from board.All we want to know is if the board is sending the 120v out to motor.
Customer: replied 7 months ago.
I am able to decouple the plastic connector but still cant get to the leads
Expert:  airheatman replied 7 months ago.
The leads of your meter should stick into the connector once unplugged.
Customer: replied 7 months ago.
Crap. What i have is a voltage detector. There are no leads on it
Expert:  airheatman replied 7 months ago.
Yeah we need a meter with leads that tells us exact voltage Walmart sells for about 10 to 15 bucks if you want to grab one.
Customer: replied 7 months ago.
Ok. I will go out and grab one. Should i reply again once i have it?
Expert:  airheatman replied 7 months ago.
Yes just come back to the question and we will go from here.Make sure to get one designed to read AC volts
Customer: replied 7 months ago.
Ok
Expert:  airheatman replied 7 months ago.
Look forward to helping you figure this out.
Customer: replied 7 months ago.
Ok. Got the volt tester
Expert:  airheatman replied 7 months ago.
Great lets unplug the connector and put meter leads in the side supplying power and see if we get 120v on call for heat.
Customer: replied 7 months ago.
So the side coming out of the infuser or the other side?
Expert:  airheatman replied 7 months ago.
The side coming from the control board.There will of course be nothing from fan since it is unplugged.
Customer: replied 7 months ago.
I am not getting anything. But i may not be doing it right
Expert:  airheatman replied 7 months ago.
Can you attach a photo of where you are checking?
Customer: replied 7 months ago.
Here you go
Expert:  airheatman replied 7 months ago.
Excellent.You are doing right. Now remember though we must have bottom panel in place or door switch held in to get power.
Customer: replied 7 months ago.
What is the right setting on this thing. I have been holding in the door switch as well
Expert:  airheatman replied 7 months ago.
Turn the dial around to 25 where the V with squiggly line is.
Expert:  airheatman replied 7 months ago.
250 not 25
Customer: replied 7 months ago.
Not getting anything
Expert:  airheatman replied 7 months ago.
Still getting light on board?
Expert:  airheatman replied 7 months ago.
Lets do one more test.Jump the R and W terminals where thermostat wires connect, hold door switch in and see if we get anything.http://i.imgur.com/JprQdYv.png
Customer: replied 7 months ago.
Yes. One i push the door switch in the red light comes on
Expert:  airheatman replied 7 months ago.
Lets do one more test.Jump the R and W terminals where thermostat wires connect, hold door switch in and see if we get anything.http://i.imgur.com/JprQdYv.png
Customer: replied 7 months ago.
I see the r and W
Expert:  airheatman replied 7 months ago.
Take a jumper wore or pair of needle nose and connect R and W
Customer: replied 7 months ago.
So twist r and w together? Then what?
Expert:  airheatman replied 7 months ago.
No do not twist wires, connect the terminals on board.http://i.imgur.com/JprQdYv.png
Customer: replied 7 months ago.
I am sorry. I dont get it
Expert:  airheatman replied 7 months ago.
Can you see the image I sent showing a jumper wire from R to W?
Customer: replied 7 months ago.
Yes. But what do i use to jump them? Do i disconnect what is there now? Maybe this tester doesnt work
Expert:  airheatman replied 7 months ago.
You can use a piece of wire or use a pair of needle nose pliers to jump.To verify meter is working, stick probes into a known working receptacle plug
Customer: replied 7 months ago.
Ok so the meter works. Tested it on a battery. So. Do i leave wires connected to r and w? What do i do with the pliers?
Expert:  airheatman replied 7 months ago.
You can leave wires connected. Just touch one side of pliers to R and the other to W.
Customer: replied 7 months ago.
Ok did that Now what?
Expert:  airheatman replied 7 months ago.
Door button In ? If so we should immediately get voltage to inducer
Customer: replied 7 months ago.
Nothing
Expert:  airheatman replied 7 months ago.
Lets do one more test then.Locate the terminals on board marked XFMR H and XMR-N , set meter to the 50 Volt setting and see f transformer is sending 24v to board.
Customer: replied 7 months ago.
Do i unplug them?
Expert:  airheatman replied 7 months ago.
NO leave the wires connected to board
Customer: replied 7 months ago.
Then how do i connect the leads?
Expert:  airheatman replied 7 months ago.
Just hold one lead on the XFMR-H and One on the XFMR-N.
Customer: replied 7 months ago.
On the actual wire or stick it in where the wire is connected?
Expert:  airheatman replied 7 months ago.
On the terminall where wire connects to board.
Customer: replied 7 months ago.
Ok. I will try. There isnt much room to get the lead in there
Expert:  airheatman replied 7 months ago.
Standing by
Customer: replied 7 months ago.
I need to step out for a few. Be back shortly
Expert:  airheatman replied 7 months ago.
Just let me know.
Customer: replied 7 months ago.
I think I have to get another volt tester. The leads don't reach anything.
Expert:  airheatman replied 7 months ago.
No problem. WE can go from here when ready
Customer: replied 7 months ago.
never mind. I didn't realize the leads had caps on them. The issue I am not having is I am not able to connect the leads to XMFR -H and N. There is a cap on the wire
Customer: replied 7 months ago.
The only way to touch the leads to them is to unplug them which won't help
Expert:  airheatman replied 7 months ago.
OK unplug wires then and stick leads into the female terminals coming from transformer.
Customer: replied 7 months ago.
I am not getting any readings no matter what i do
Expert:  airheatman replied 7 months ago.
How about the wires going into transformer high voltage side
Customer: replied 7 months ago.
Something isnt right. Nothing seems to give me a reading on this tester
Customer: replied 7 months ago.
Except sticking it in an outlet
Expert:  airheatman replied 7 months ago.
Is door button held in during testing?
Customer: replied 7 months ago.
Yes
Expert:  airheatman replied 7 months ago.
Locate the main power wires where they connect to board and see if we have 120v there, Board may be the whole problem
Customer: replied 7 months ago.
Is this it?
Customer: replied 7 months ago.
Found them. Getting a reading
Expert:  airheatman replied 7 months ago.
OK sounds like the board is going to be the culprit.Power in but not out of board
Customer: replied 7 months ago.
Wonderful
Expert:  airheatman replied 7 months ago.
If you have further questions, please let me know.Thanks for letting me work with you.If my answer has been polite, professional,and thorough, please click one of the ratings before you go. If you still need help let me know!.Expert is not paid for assisting you until you rate answer.Feel free to follow up for 30 days at no additional cost. Bonus always appreciated if you feel justified.To rate answer, please select one of the stars below.
Customer: replied 7 months ago.
But why does the air and fan work?
Expert:  airheatman replied 7 months ago.
Hmm would not expect either to work if no 120 from board to transformer or 24v out of transformer.
Customer: replied 7 months ago.
Furnace kicked on when i changed the tstat to air
Expert:  airheatman replied 7 months ago.
Furnace as in Heat mode?
Customer: replied 7 months ago.
Air mode. Would it be a good ide to put the door(s) on at least the bottom and try the infuser power again?
Expert:  airheatman replied 7 months ago.
Lets try that
Customer: replied 7 months ago.
No dice
Customer: replied 7 months ago.
So mu guess is the board fried when the power came back on? But that doesnt explain why the ac works
Customer: replied 7 months ago.
I am totally stumped
Expert:  airheatman replied 7 months ago.
I am suspecting an issue with the board,Might be best to get an onsite tech to verify though before just start changing parts