Trane xl90 Furnace - won't start up


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Old 10-01-09, 03:18 AM
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Trane xl90 Furnace - won't start up

Hello. I live in NE ohio so it is starting to get cold. Yikes just in time to start the heater to find it doesn't work. The A/C portion starts and runs fine, just the heat doesn't work. Here is my specs

Trane xl90
"Super Efficient Gas Furnace"
Mod TVC120B960AC
Ser 02500074
White Rogers 50E47-60

The vent fan comes on and that is it. I have 29 volts coming from the transformer (red wire to red terminal). Essentially 0v on the "B/C" terminal (I thought there should be approx 24 on this as well, no?). I can't remember if there is a sparking unit or glow so I don't know what to look for there either.

I replaced my thermostat this summer with a Ritetemp 6080 (Home Depot) digital display.

Not freezing yet but my kids are looking at me with disgust in the morning. Yikes

Also, there the red light on the White Rogers dealio isn't lit in any way.
 
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Old 10-01-09, 01:19 PM
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At the t-stat, do you have W1 and W2 wired up? and same color matching on W2 and W1 on the board?

The model # you've given is not a valid number should be like TUX------

On the board, the call for heat should be a fast flashing LED light.
 
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Old 10-01-09, 03:21 PM
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Originally Posted by Jay11J View Post
At the t-stat, do you have W1 and W2 wired up? and same color matching on W2 and W1 on the board?

The model # you've given is not a valid number should be like TUX------

On the board, the call for heat should be a fast flashing LED light.
Yes you are correct, the model number looks more like a "TUC" instead of a "TVC" Sorry about that chief.

On the t-stat there is a "w" and "w2" and I have my white connected to the "w"

For the red light - nothing. When I raise the temp on the t-stat and call for heat, nothing happens with the read light. The only apparent activity is the vent fan coming on
 
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Old 10-01-09, 03:24 PM
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Originally Posted by Jay11J View Post
At the t-stat, do you have W1 and W2 wired up? and same color matching on W2 and W1 on the board?

The model # you've given is not a valid number should be like TUX------

On the board, the call for heat should be a fast flashing LED light.
Two things.

1) thanks so much for taking your time to help me out. I love the internet and people like you make it just that much better.

2) Also on the Trane there is only one "W" and therefore only one white wire. That one white wire goes to the "w" on the t-stat. Should I have something different?
 
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Old 10-01-09, 03:35 PM
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Originally Posted by nvrminds View Post
2) Also on the Trane there is only one "W" and therefore only one white wire. That one white wire goes to the "w" on the t-stat. Should I have something different?
Your TUC is the XE90 furnace, not XL90. XL is a two stage furnace, so that's why I brought up the W1 and W2.

So W and W is correct. If the inducer fan is just coming on, does that fan stay on the whole time or does it shut down?

Do you have a meter? Also on your furnace, do you have one pipe or two pipe going outside?
 
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Old 10-01-09, 06:07 PM
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Originally Posted by Jay11J View Post
Your TUC is the XE90 furnace, not XL90. XL is a two stage furnace, so that's why I brought up the W1 and W2.

So W and W is correct. If the inducer fan is just coming on, does that fan stay on the whole time or does it shut down?

Do you have a meter? Also on your furnace, do you have one pipe or two pipe going outside?
The Furnace cover says XL90 so that is why I stated that. It says "High Efficiency" on that cover as well

Only the inducer comes on. I don't hear any popping if there is a spark ignitor or see a glow if it is a glow ignitor

The fan stays on as long as I am calling for heat and I keep power going to the system.

I have a digital voltmeter.

I apologize for the slow response. I have a group that meets at my house on Thurs so I was preoccupied.
 
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Old 10-01-09, 06:49 PM
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Must be an older model.

Up by the burner there is a hot surface ignotor (right hand side), and it should glow after about 30 sec of the fan running.

Undo the plug and put the meter on the plug that the ignitor goes into. You should see 120 volts (sometime less)

If you are not seeing that, then we need to check your pressure switches.
 
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Old 10-01-09, 07:12 PM
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I might have tracked it down to the pressure valve sensor (or what ever real name it has). I found on one side of the relay the 29 volts but nothing on the other side. When I jumper-ed it, furnace came on and worked.

This is the a round 3 in diameter silver device (attached to the left hand wall) with a relay on it.

Do you think I have it?

If so, is this part easy to come by? How do I find it locally? I got one of the clamps off the tube (one leading into the device) but couldn't get the tube off with light pressure. Does it need to be treated rough?
 
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Old 10-01-09, 07:15 PM
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Pressure switch.

Do not leave the jumper on it. Where does the hose from this go to? Undo the hose from the switch and blow into it to make sure it's not plugged up with something.

Do you have one or two pipes on the furnace? (PVC)

I am heading to bed.. been under the weather.. will be back tmrw.
 
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Old 10-01-09, 08:13 PM
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Originally Posted by Jay11J View Post
Pressure switch.

Do not leave the jumper on it. Where does the hose from this go to? Undo the hose from the switch and blow into it to make sure it's not plugged up with something.

Do you have one or two pipes on the furnace? (PVC)

I am heading to bed.. been under the weather.. will be back tmrw.

Oops, sorry about not answering the pvc question. One pipe

The hose goes down to a port below the vent fan. Not right next to it but part of the assembly (army green in color).

I will try to blow on the hose.

I also when outside and checked the flu to see if there were obstructions. There were a hand full of leaves dancing around inside the exhaust but there seemed to be plenty of pressure coming out. But does that mean it is full pressure?

Get some sleep and hope you feel better. Thanks for your willingness to help some poor sole who you don't even know. Quite generous. Good night.
 
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Old 10-02-09, 04:16 AM
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Originally Posted by Jay11J View Post
Pressure switch.

Do not leave the jumper on it. Where does the hose from this go to? Undo the hose from the switch and blow into it to make sure it's not plugged up with something.

Do you have one or two pipes on the furnace? (PVC)

I am heading to bed.. been under the weather.. will be back tmrw.
Also this morning I pulled the clear tube off the pressure valve and blew down it. Seemed to blow pretty freely.

Oh, good morning.
 
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Old 10-02-09, 05:31 PM
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Ok, then take the hose off the fan housing, and then set the systtem to call for heat.

Suck on the hose softly and hold it there to see if anything happens.. Nothing happens for a minute, then blow on it just enough to trip the switch. and see if anything happens.

I'm feeling better now! :-)
 
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Old 10-02-09, 11:44 PM
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Originally Posted by Jay11J View Post
Ok, then take the hose off the fan housing, and then set the systtem to call for heat.

Suck on the hose softly and hold it there to see if anything happens.. Nothing happens for a minute, then blow on it just enough to trip the switch. and see if anything happens.

I'm feeling better now! :-)
Glad to hear you are feeling better. I waited yesterday for a reply and I didn't see anything and figured you had taken a turn for the worse. As I am on a different computer this morning (2am - yikes) I find your reply. I must have the thread displaying in reverse order or something because it wasn't were I thought it would be when looking last night on my laptop. I must have been scrolling right past it. Great to hear you feeling better.

Ok, so I pretended I was at the doctors sucking on that clear hose. I kept my sucking going for about 15 sec (very light sucking) and sure enough the glow plug came on.

So that must mean the pressure valve is working and the vacuum from the vent fan isn't getting the job done. Mmm, I placed a small piece of paper over the hole I pulled the hose from. It did hold it there as if being sucked. I couldn't feel anything with my finger but it did seem to have a pull on a piece of paper. Very interesting. Maybe the switch is going bad and just needing the extra pull I might be able to provide? Waiting for your next step.

Probably hear from you in the morning.
 

Last edited by nvrminds; 10-03-09 at 12:11 AM.
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Old 10-03-09, 02:24 AM
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By the way, I had said it has one exhaust. On the left side of the vent motor is the white PVC pipe leading out to the great outdoors. On the right side of the motor is also a white PVC pipe but it goes up about 8 inches. It terminates inside the furnace. There is a screen mesh wrapped on the top of it.

Would a picture help you in anyway? How do I get that to you?
 
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Old 10-03-09, 05:25 AM
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Yes photos help! You need up upload your photo to a host site like yahoo or imageshack.us then then post the url address on the photo pop up box.
 
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Old 10-03-09, 08:26 AM
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Trane xl90 Furnace
 
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Old 10-03-09, 10:35 AM
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Oh wow.. that's an old Trane!

If I recall back in my Tech School days, you need to prime the system.

Looks like there is an open 1/2 pipe, (drain) pour some water down that opening.


See if that helps.
 
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Old 10-03-09, 11:54 AM
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You have confirmed that in all likelyhood, the electrical switch on the pressure switch is good.

But your test does not conclusively rule out a teeny hole in the vacuum diaphram by you continously sucking on the tubing.

You must gently suck on the tube, and then while doing so, pinch off the tubing absolutely 100%, and stop sucking, and keep it pinched off, to make sure that if the diaphram does not have the teeniest of tears or whatever, that the switch then opens up and the flame goes out. If it stays running, then indeed you have a venting issue, not a pressure switch issue.
 
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Old 10-03-09, 12:29 PM
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Originally Posted by Jay11J View Post
Oh wow.. that's an old Trane!

If I recall back in my Tech School days, you need to prime the system.

Looks like there is an open 1/2 pipe, (drain) pour some water down that opening.


See if that helps.
Ok, so I tried pouring water down the 1/2 pipe. Tried to see if that would start it and it didn't.

I next pulled the clear hose and started sucking on it ever so slightly until I heard the rely click. The glow ignitor came on and I continued to suck on the hose as I folded it several times. It didn't stay on.

Ok, is there a more sure way of guaranteeing I am not loosing any vacuum when I fold it? Is there a better way to seal up the hose to ensure 100%?

That pressure sensor is apparently 250 dollars. Can you all just try and make it the tubing?

Hey, how do I know if the tubing isn't the part leaking? Is it special tubing or is it something a typical local store would carry?
 

Last edited by nvrminds; 10-03-09 at 12:57 PM.
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Old 10-03-09, 05:04 PM
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You could try moving the tubing, and close off one end, and blow in the other, and see if you can feel any leaks/cracks.

As for replacement hose, You may have better luck at an Automotive store than home centers.
 
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Old 10-03-09, 05:09 PM
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Originally Posted by Jay11J View Post
You could try moving the tubing, and close off one end, and blow in the other, and see if you can feel any leaks/cracks.

As for replacement hose, You may have better luck at an Automotive store than home centers.
Any suggestions to confirm a 100% no leak seal after getting the switch to activate? Do you feel that when I am sucking on the tube and getting the switch to activate, that I should be able to stick my tongue in the hose and that would be 100%? What does a professional do?
 
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Old 10-03-09, 05:52 PM
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The pro has a gauge that reads the pressure, and compair to the number on the switch.
 
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Old 10-03-09, 07:27 PM
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excellent. Thanks for the advise. I will change out the tube and hope to see if that is it. If I change that out and it doesn't fix it, is it unanimous that it is the pressure switch?

Where is the best place to purchase it? Any ideas?
 
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Old 10-04-09, 04:33 AM
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Check with your dealer, some times you may get a better price on it.. Otherwise, hunt around on line. Just make sure you get the matching switch. (Pressure rating)
 
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Old 10-06-09, 01:24 PM
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Originally Posted by Jay11J View Post
Check with your dealer, some times you may get a better price on it.. Otherwise, hunt around on line. Just make sure you get the matching switch. (Pressure rating)
Case closed. here is what I did.

Indications were leading to a possible pressure switch. Not good. Most of the time these are 50 to 70 bucks but for my furnace it was $250 from a distributor. No joke! But . . .

There was a clear tube that ran from the vent assembly to the pressure switch. I disconnected the side at the vent and plugged in a 4 foot length of tubing. I poured water down the tube and created a horse shoe to allow the water to pool there. I marked level and then I called for heat. The pressure switch had a rating of 1.33" and so I expected the water column to be sucked up approx 1.33" and it did for the most part. It wasn't. More like a quarter of an inch. See this pic for clarity




A Jay I know here in Cleveland is an Engineer and a incredible thinker. He made the drawing and gave me the idea

This means that there wasn't enough vacuum. I had earlier gone outside to see if there was an obstruction in the PVC that leads outside. There were some leaves but there seemed to be some pretty good plowing coming from the furnace.

I disconnected the PVC pipe that goes into the top of the furnace and tried the test again. Not perfect but way better. I hooked up my leaf blower and let it blow towards the outside for about 3 mins. I found tons of debris outside so even though they didn't stop the air flow going out, the leaves must have reduced it significantly.

I also heard some stuff rattling around (debris) inside the vent chamber. I hooked up a vacuum to the 1" pvc pipe at the bottom and sucked some crud out as well. Put back together and it worked great. I have heat.

I just want to thank everyone that has helped me work through this problem. I hope that this post can help someone else with similar issues. I saved at least $400 I am sure doing this with your all's help. Much "thank you's"
 
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Old 10-06-09, 06:58 PM
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Glad to hear you got it up and going.

Yeah with out taking a reading to see what's going on, and you got it.
 
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Old 10-03-11, 05:03 PM
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Ecman51, I know this is a way old post, but hopefully you are still around since I am trying to figure out what is wrong with my furnace which won't start and am trying to rule things out like this person was trying to do. OK, background story as follows: I have a Intertherm furnace(Nordyne). I think it is a mid efficiency one, for sure not a high efficiency one. Per diagnostic code, "pressure switch stuck on close". Have done quite a bit of trouble shooting, but not getting anywhere. Now nothing happens at all when I turn the thermostat to heat. When this first started a few days ago, I very gently blew through the rubber hose that connects to the pressure switch and for good measure gently blew through the other end of it where it connects to a metal nipple on the surface of the furnace "body" which I think somehow connects to the draft inducer. It actually did start up and I had to lower the temp. since it was getting too hot. I was all happy, but then the next morning noticed no heat again so was no longer all happy. It did again turn on by "itself" the following day, but nothing since then. Yesterday, removed the pressure switch and noticed some water came out of it(during the summer the humidifier or something backed up and the water was probably from that). I shook it out and let it dry out for half a day and put it back into the furnace. Still same code showing. I took the switch off again and blew through the plastic nipple and can hear the diaphragm move and had it checked at a local parts store and they did a meter reading or something and said it is working. I then turned off the furnace again and removed the wire that goes into the pressure switch and put the power back on, bypassed the power off since the furnace door was open(only did it for a few seconds since not good to be bypassing the pressure switch) and the draft inducer did kick in(saw the fan that is visible spin very robustly and heard it so assume that the draft inducer is working). I haven't checked the flue yet for any obstruction since it seems like it is not going to be easy to disconnect that and not sure if any not good gases will be left in there(I would think not since it hasn't been used much). Is that correct? The only other thing I can think of is that the circuit board is somehow not good or there is some kind of "lock down" that needs to be reset since it seems the problem has to be somewhere in the beginning of this whole heating cycle since if it were later on, there would be some other diagnostic code so then think this pressure switch code, stuck on close, wouldn't be showing up. From my understanding in the heating sequence the pressure switch usually is first on open, furnace "senses" that, which lets the draft inducer do its thing, which then closes the pressure switch, and then the rest of the sequence goes on as far as I understand things, but maybe I am not understanding correctly. Well, that is about it, I think. Oh no, I did forget something. When I turn the thermostat fan to "on", the fan does run. I assume that fan is the same fan as the furnace blower fan so that is working. Hope you're still around somewhere. Please help. Not a good time financially to be buying a new furnace(would end up having to do that since it is 14 years old and I know how much just those service calls are and how much having a part replaced is if not done by one's self and already put a fair amount of money into this furnace/air unit part already, but really think there is a relatively simple fix that I can do myself or maybe I am wrong.

Thanks,
Ceci
 
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Old 10-03-11, 05:11 PM
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CECI, please check your thread that you previously posted!
 
 

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