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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: 1 year ago.
Category: HVAC
Expert:  Tim H. replied 1 year 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 1 year ago.
Model# *****
Expert:  Tim H. replied 1 year ago.

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

Customer: replied 1 year ago.
Are you referring to the furnace filter I replaced? Or is there another spot that could be plugged.
Expert:  Tim H. replied 1 year 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 1 year 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 1 year 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 1 year ago.

Part # *****

Customer: replied 1 year ago.
I am not seeing that. Where would it be?
Expert:  Tim H. replied 1 year ago.

Are your burners at the very top of furnace?

Customer: replied 1 year ago.
They are at the very bottom.
Expert:  Tim H. replied 1 year ago.

Downflow furnace?

Customer: replied 1 year ago.
From the front would it look like this?
Customer: replied 1 year ago.
I believe it's downflow?
Expert:  Tim H. replied 1 year 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 1 year ago.
Well, the filter is at the top...
Expert:  Tim H. replied 1 year ago.

That's a downflow

Customer: replied 1 year ago.
The picture I sent... Is that the switch?
Customer: replied 1 year ago.
Also is there a way to test it with a meter?
Expert:  Tim H. replied 1 year ago.

Hang on, I'm running that number/

Expert:  Tim H. replied 1 year ago.

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

Customer: replied 1 year ago.
What does that mean...
Expert:  Tim H. replied 1 year 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 1 year ago.
I can't really tie them together. They look like this.
Expert:  Tim H. replied 1 year ago.

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

Customer: replied 1 year ago.
connect the two leads with a paperclip?
Expert:  Tim H. replied 1 year ago.

yup

Customer: replied 1 year ago.
Not exactly sure this is what you meant (see picture). But the error code is still blinking
Expert:  Tim H. replied 1 year ago.

Sure it's making connection? In there securely?

Customer: replied 1 year ago.
I even wiggled it around a little bit
Expert:  Tim H. replied 1 year ago.

OK, put those leads back.

Customer: replied 1 year ago.
Done. And still have an error code
Expert:  Tim H. replied 1 year ago.

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

Customer: replied 1 year ago.
Having trouble finding that one. Unless it is this? But the red button doesn't really push
Expert:  Tim H. replied 1 year ago.

send a pic?

Customer: replied 1 year ago.
Picture attached
Expert:  Tim H. replied 1 year ago.

Where is that located?

Customer: replied 1 year ago.
On top of burner area. Connects directly to the other switch we were working with
Customer: replied 1 year ago.
Zoomed out picture
Expert:  Tim H. replied 1 year ago.

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

Customer: replied 1 year ago.
What would that look like. Or where would it be
Expert:  Tim H. replied 1 year ago.
Customer: replied 1 year ago.
Oh, yes. It's right above that area
Expert:  Tim H. replied 1 year ago.

Is there a small disk shaped device with red reset?

Customer: replied 1 year ago.
Unless I am missing something I don't see anything like that
Expert:  Tim H. replied 1 year ago.

Parts list shows a limit inducer

Customer: replied 1 year ago.
Which would be the disk shape with a red button?
Expert:  Tim H. replied 1 year 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 1 year ago.

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

Customer: replied 1 year ago.
Yeah that's the frustrating thing. I feel like it should be there somewhere. But can't see it.
Expert:  Tim H. replied 1 year ago.

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

Customer: replied 1 year ago.
Thought I had found it. The only other wires going to it are here. But no red button
Expert:  Tim H. replied 1 year 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 1 year ago.
Still an error code
Expert:  Tim H. replied 1 year 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 1 year ago.
No. Don't see any switches down there
Expert:  Tim H. replied 1 year ago.

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

Expert:  Tim H. replied 1 year ago.

Did you search for a part that looks like this?

Expert:  Tim H. replied 1 year 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 1 year ago.

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

Expert:  Tim H. replied 1 year 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.