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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Customer Question

Customer: Hi ***** *****! Happy New year! Are you available for a question?
JA: Thanks. Can you give me any more details about your issue?
Customer: Yes okay my Trane xv80 furnace was blowing cold air last night (well tepid) and i went down and it was flashing 4 times..looked it up and indicated a tempature issue...yep the filter ws a disaster! whoops...black and filthy. I replaced it but cant seem to find a reset so every time I turn it back on no heat. I googled every direction to find a picture of it but I cant find one. What is your advice? I am a total new to all this...and im cold, lol
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Submitted: 11 months ago.
Category: HVAC
Expert:  airheatman replied 11 months ago.

Lets start by looking on the blower housing for a limit with a small button in between the wires that pushes in to reset.

Customer: replied 11 months ago.
okay thanks! this is Chinese to me. I looked around and didnt see any obvious button. there are several black boxes on it maybe under those?
Expert:  airheatman replied 11 months ago.

Should have 2 yellow wires going to it

Customer: replied 11 months ago.
ok be right back! ty
Expert:  airheatman replied 11 months ago.

Take your time.Should be on the housing of the blower

Customer: replied 11 months ago.
im going to look but maybe I may need to text you a pic
Expert:  airheatman replied 11 months ago.

Let me see if I can find a pic.

Customer: replied 11 months ago.
K I found two yellow wires they went down to what i think is the cover on a blower. they each plug into either side of a little black disc- smaller than a dime but there is no red button there...
Expert:  airheatman replied 11 months ago.

Can you attach picture

Customer: replied 11 months ago.
okay let me see how to do that...I cant shoot it and text right from my iphone right?
Customer: replied 11 months ago.
wait im going to take laptop down and shoot...just a momment
Expert:  airheatman replied 11 months ago.

Lets do this follow those yellow wires and see if there are any resettable limits that have a button to pus\hk,Should have a couple around burners also.

How long has it been since furnace quit?The non ressetables should cool down and reset themselves after several minutes.

If you have a paper clip icon on your page you can attach using that link.Or

You can upload the pictures using the tiny pic site .

Here is a link to the site.

http://tinypic.com/

Click on Browse , select the file from your folder.then click UPLOAD NOW.

They will give you a quote to enter in the box to verify you are a human.Enter the quote and click UPLOAD NOW

You will see your picture on right side of screen.

Then copy the link URL for email & IM

Paste that link here on the site.

Customer: replied 11 months ago.
okay I think these are upside down.
SO it started blowing tepid air last night I shut it off went to bed. my house is 57 lol...i went down this moring and the filter is BLACK (whoops) I replaced with a new one, but now it still kicks on but blows tepid air.
Expert:  airheatman replied 11 months ago.

Excellent job. That is the limit I suspect. Now since you have removed door panel the board should reset and limit should definitely have had time to cool down. Hold door switch in or put panel back and see if furnace will work now or we still get error code.

Customer: replied 11 months ago.
okay I did that twice already this morning and still kicks on but blows tepid.
Customer: replied 11 months ago.
i had to shove my laptop under upside down lol glad pics came out ok! lol
Customer: replied 11 months ago.
same code 4 flashes but Ill try again?
Expert:  airheatman replied 11 months ago.

OK lets check the other limits.Look above burners for ones with reset buttons.

http://i.imgur.com/CGkB9sa.jpg

Customer: replied 11 months ago.
okay where is that?
Customer: replied 11 months ago.
I literally looked everywhere accessible. ill take anther picture
Expert:  airheatman replied 11 months ago.

Take me a pic with top panel removed where burners are

Customer: replied 11 months ago.
okay THAT was the missing link! I didnt realize that top panel came off!
Okay I have a pic and I found the yellow wires and two of those but the little red buttons didnt feel like a good click or reset feeling- they just wiggled a little. Ill send a pic n a second
Customer: replied 11 months ago.
there was one on either side and I wiggled and tried to "click" them both...
Expert:  airheatman replied 11 months ago.

If none of them will reset it is possible one of the limits has opened and stuck open.

There should be 4 limits on the furnace.To determine which one is stuck open we can bypass each one until we get error code to go away and furnace to ignite.

One is on blower housing that you sent picture of. two are the flame rollouts with buttons and other is about the size of a credit card above burners in center of furnace vestibule.

Expert:  airheatman replied 11 months ago.

To bypass them one at a time. unplug wires from limit and connect wires together using a small fuse, wire or straightened paper clip

http://i.imgur.com/Aqd9O0f.png

http://i.imgur.com/WqmGzzO.png

Customer: replied 11 months ago.
thud*....that was me fainting...lol
Expert:  airheatman replied 11 months ago.

You have got this.I am here to guide you .Together I am confident we can get this figured out.

Customer: replied 11 months ago.
okay so step by step for this newb...Do the paperclip then try to fire up?
then repeat for each station?
Or do them all then fire it up at the end?
Customer: replied 11 months ago.
okay great...if you can sequence this for me that would be great. like step by step
Expert:  airheatman replied 11 months ago.

One limit at a time.We are trying to find which limit is "open",

Lets start with that one on blower. Disconnect the 2 yellow wires, put the paper clip in wire connections to close circuit.Make sure paper clip can not touch metal and short out. The power on and see if error code is gone.If not we will move to next one.

Customer: replied 11 months ago.
the ones/wires in the picture are not yellow but I look for yellow ones right?
Expert:  airheatman replied 11 months ago.

I am showing tem as yellow. See below

Customer: replied 11 months ago.
okay Im going to come back to this in about two hours are you still going to be available?
Expert:  airheatman replied 11 months ago.

Absolutely.WE will go from here

Customer: replied 11 months ago.
okay we are back and ready to go try this
Expert:  airheatman replied 11 months ago.

OK I am standing by.Let me know what you need

Customer: replied 11 months ago.
okay which is the blower? having trouble figuring out where to start
Expert:  airheatman replied 11 months ago.

Lets jump this one first

Customer: replied 11 months ago.
okay the first one didnt fix problem. that was the bottom one near the fan correct?
Customer: replied 11 months ago.
what next
Expert:  airheatman replied 11 months ago.

Next lets do that one in furnace vestibule that is about the size of a credit card.

http://i.imgur.com/LNCrUvz.jpg

Customer: replied 11 months ago.
okay doing now
Expert:  airheatman replied 11 months ago.

Standing by

Customer: replied 11 months ago.
okay still blinks four times whats next
Customer: replied 11 months ago.
flame rollout left and right...any order??
Expert:  airheatman replied 11 months ago.

Do each of those little ones above burners.Doesnt matter which first

Customer: replied 11 months ago.
okay still blinking four times after the last two are checked. Now what?
Expert:  airheatman replied 11 months ago.

Follow that circuit and verify there are absolutely no other limits in the circuit.(Sometimes diagrams vary from what you actually have). Then unplug the 12 pin connector on board, make sure all wires are seated in connector so they make contact with board when plugged in.

Customer: replied 11 months ago.
okay. done
Expert:  airheatman replied 11 months ago.

Still same code?

Customer: replied 11 months ago.
it did a code three
Expert:  airheatman replied 11 months ago.

Whole different can of worms. Now saying you have a pressure switch open. Power cycle furnace with switch by turnin gon and off and see what we get

Customer: replied 11 months ago.
done... no change...
Expert:  airheatman replied 11 months ago.

What code now?

Customer: replied 11 months ago.
still 3
Expert:  airheatman replied 11 months ago.

Does the small vent motor come on?

Customer: replied 11 months ago.
exhaust vent?
Expert:  airheatman replied 11 months ago.

Remove the small rubber hose from exhaust motor housing leave attached to pressure switch suck on hose and see if pressure switch closes and furnace lights

Customer: replied 11 months ago.
did that same thing. no change...we could feel valve moving when sucking and blowing but still 3 lights
Expert:  airheatman replied 11 months ago.

Sounds like you may have a board going out.Really hate condemning a board, but when board syas we have an open limit , we prove all limits are closed, The board says we have an pen pressure switch and we can hear switch closing,board seems to be giving false codes,