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Tim H.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3971
Experience:  Experienced in all aspects of HVAC, both residential and commercial.
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I have a Trane xr90 with 4 blinking lights error code.

Customer Question

I have a Trane xr90 with 4 blinking lights for the error code. Furnace is blowing cold air.
JA: Sometimes HVAC issues that that you think will be really complicated end up being easy to fix. The HVAC Technician I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so we can help you best.
Customer: The furnace had a dirty filter which I replaced. But I can't find a reset switch anywhere
JA: Is there anything else important you think the HVAC Technician should know?
Customer: It's a Trane xr90 furnace
JA: Our top HVAC Technician is ready to take your case. Just pay the $5 fully refundable deposit and I'll fill the HVAC Technician in on everything we've discussed. You can go back and forth with the HVAC Technician until you're 100% satisfied. We guarantee it.
Submitted: 9 months ago.
Category: HVAC
Expert:  Tim H. replied 9 months ago.

Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need. Please be patient as many times we work with several customers at once.

Can I get full model number of the unit? This will be found inside the door on a tag.

Customer: replied 9 months ago.
Model# *****
Expert:  Tim H. replied 9 months ago.

THis will most likely be an open high limit switch, more than likely caused by the plugged filter.

Customer: replied 9 months ago.
Are you referring to the furnace filter I replaced? Or is there another spot that could be plugged.
Expert:  Tim H. replied 9 months ago.

No, because the furnace probably got too hot, there is an over temperature switch that is probably open (electrically) and will need replacement.

Customer: replied 9 months ago.
I read that some furnaces have a switch that can be reset. Does this model have one of those? Or will it need to be replaced.
Expert:  Tim H. replied 9 months ago.

Looks like this. This one cannot be reset. It should reset itself when furnace cools down. If not, will need replacement.

Expert:  Tim H. replied 9 months ago.

Part # *****

Customer: replied 9 months ago.
I am not seeing that. Where would it be?
Expert:  Tim H. replied 9 months ago.

Are your burners at the very top of furnace?

Customer: replied 9 months ago.
They are at the very bottom.
Expert:  Tim H. replied 9 months ago.

Downflow furnace?

Customer: replied 9 months ago.
From the front would it look like this?
Customer: replied 9 months ago.
I believe it's downflow?
Expert:  Tim H. replied 9 months ago.

Although this is not the actual switch you need, here's what it looks like from the front view which is what you will see.

Customer: replied 9 months ago.
Well, the filter is at the top...
Expert:  Tim H. replied 9 months ago.

That's a downflow

Customer: replied 9 months ago.
The picture I sent... Is that the switch?
Customer: replied 9 months ago.
Also is there a way to test it with a meter?
Expert:  Tim H. replied 9 months ago.

Hang on, I'm running that number/

Expert:  Tim H. replied 9 months ago.

That's it, but not the right part in there.

Customer: replied 9 months ago.
What does that mean...
Expert:  Tim H. replied 9 months ago.

Turn furnace power off, take the two leads off that switch, tie the metal ends together and power back on. If the flash code goes away, that is your issue.

Customer: replied 9 months ago.
I can't really tie them together. They look like this.
Expert:  Tim H. replied 9 months ago.

Take a paperclip. This is low voltage. Just don't touch the metal paperclip on anything.

Customer: replied 9 months ago.
connect the two leads with a paperclip?
Expert:  Tim H. replied 9 months ago.

yup

Customer: replied 9 months ago.
Not exactly sure this is what you meant (see picture). But the error code is still blinking
Expert:  Tim H. replied 9 months ago.

Sure it's making connection? In there securely?

Customer: replied 9 months ago.
I even wiggled it around a little bit
Expert:  Tim H. replied 9 months ago.

OK, put those leads back.

Customer: replied 9 months ago.
Done. And still have an error code
Expert:  Tim H. replied 9 months ago.

Look for a part that looks like this. Perhaps on inducer motor. Press the red button in the center.

Customer: replied 9 months ago.
Having trouble finding that one. Unless it is this? But the red button doesn't really push
Expert:  Tim H. replied 9 months ago.

send a pic?

Customer: replied 9 months ago.
Picture attached
Expert:  Tim H. replied 9 months ago.

Where is that located?

Customer: replied 9 months ago.
On top of burner area. Connects directly to the other switch we were working with
Customer: replied 9 months ago.
Zoomed out picture
Expert:  Tim H. replied 9 months ago.

Can you find your inducer motor? Is there one on there?

Customer: replied 9 months ago.
What would that look like. Or where would it be
Expert:  Tim H. replied 9 months ago.
Customer: replied 9 months ago.
Oh, yes. It's right above that area
Expert:  Tim H. replied 9 months ago.

Is there a small disk shaped device with red reset?

Customer: replied 9 months ago.
Unless I am missing something I don't see anything like that
Expert:  Tim H. replied 9 months ago.

Parts list shows a limit inducer

Customer: replied 9 months ago.
Which would be the disk shape with a red button?
Expert:  Tim H. replied 9 months ago.

Can't find a good picture of it. Besides the one above your burners, look for any disc shaped device with a red reset.

Expert:  Tim H. replied 9 months ago.

Look for a part that looks like this. Says its on the inducer.

Customer: replied 9 months ago.
Yeah that's the frustrating thing. I feel like it should be there somewhere. But can't see it.
Expert:  Tim H. replied 9 months ago.

Follow any wires that go in and around the inducer. Other then the actual wires that power inducer motor.

Customer: replied 9 months ago.
Thought I had found it. The only other wires going to it are here. But no red button
Expert:  Tim H. replied 9 months ago.

That's it. Now do the same thing that you did with the other one. Turn power off, tie wires together, power back on.

Customer: replied 9 months ago.
Still an error code
Expert:  Tim H. replied 9 months ago.

OK, in that case you may have a bad board. We've checked all the over temperature switches. Unless there's one down in the blower area.

Customer: replied 9 months ago.
No. Don't see any switches down there
Expert:  Tim H. replied 9 months ago.

Probably a bad board, then. Or a short in the wiring between switches and board.

Expert:  Tim H. replied 9 months ago.

Did you search for a part that looks like this?

Expert:  Tim H. replied 9 months ago.

Do this if you will. A picture's worth a thousand words. If you can, take a bunch of pictures from out a ways and then close in of inside of furnace, blower, inducer, etc. So I can get a feel if we've missed anything.

Expert:  Tim H. replied 9 months ago.

If you would rather just call a technician, let me know and we can close question out.

Expert:  Tim H. replied 8 months ago.

Did you need further help with this? If not, thanks for using Just Answer and please don't forget to rate my service as that's how experts get paid (thanks in advance for any bonus left). Otherwise experts work at their own time and expense. Feel free to post back with any more questions.

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