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Phil, Mechanical Engineer
Category: HVAC
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Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Our trane XR80 furnace red light was flashing continously calling

Customer Question

Our trane XR80 furnace red light was flashing continously calling for heat but nothing happened. Called our energy company who came out and determined we needed a new thermostat. We purchased a new honeywell thermostat ans installed it then powered turned power switch to furnace on. ran for about a minute then quit. Now the red light is not lit which indicates no power to the unit. The breaker is on the switch is on and when saftey switch is pushed in (when you replace the furnace door) you can hear it hum but still no LED red light on circuit board. Is there a reset required??
Submitted: 6 years ago.
Category: HVAC
Expert:  BillyHvac replied 6 years ago.

 

Is the light on a White Rodgers control box?

 

 

Customer: replied 6 years ago.

I am not at the house right now but the red light was on the main circuit board which was white. i don't recall the name on it. We will be going there soon and will have to chat via my blackberry if required.

 

Expert:  BillyHvac replied 6 years ago.

 

Thank you....Do you have a volt meter to take with you?

 

 

Customer: replied 6 years ago.
yes, although not sure how to read it.
Expert:  BillyHvac replied 6 years ago.

 

Ok...we can get through part. Also if when you are there, if you can get me the model number from the white box I can tell you more specifically what to do.

 

I will be off line however for a while...will be back on in 2 hours. If you like I can opt out to someone who will be online.

 

 

Customer: replied 6 years ago.
I can wait Billy. we are good to go with the volt meter. Will take it over. How do I get back to chat on my bb? Just go to the URL and use my #?
Expert:  BillyHvac replied 6 years ago.

 

Correct. Just return to this same thread.

 

Talk to you soon.

 

 

Customer: replied 6 years ago.
We are here now. Let me know when u r back
Expert:  BillyHvac replied 6 years ago.

 

Hello,

 

Ready to proceed.

 

 

Customer: replied 6 years ago.
It is a white rogers control switch.
Expert:  BillyHvac replied 6 years ago.

 

Do you have the number from the control box?

 

 

Customer: replied 6 years ago.
Am here which number.
There is(NNN) NNN-NNNN
Expert:  BillyHvac replied 6 years ago.

Should be a 50E or cnt #

 

OR just give me model number of unit....

Customer: replied 6 years ago.
Cnt 03076
Expert:  BillyHvac replied 6 years ago.

 

Thank you....so we went from flashing....changed thermostat...now nothing...so the unit has never ran with the new thermostat?

 

 

Customer: replied 6 years ago.
It powered up for about a minute then quit. No more red light. Did not through breaker. So indicates no power to unit with no red light. We tried bypassing thermostat and nothing yet when we depress safety switch u can hear a hum like there is power.
Expert:  BillyHvac replied 6 years ago.

 

Ok,

 

we need bottom door off and the safety switch taped down securely...Then set meter for ac volts~ and set for scale of 200 (anything higher than 115v but lower than 500.

 

Put one lead to "line" terminal on control and one lead to ground.

 

see page 13 here for wiring help.

 

http://hvac.amickracing.com/Furnace%20Info/Gas%20Furnace%20Silicon%20Nitride%20Ignitor%20Models.pdf

 

 

Customer: replied 6 years ago.
Same schematic as on door. Not sure which is line and ground in relationship to the thermostat connection
Expert:  BillyHvac replied 6 years ago.

We are not looking at thermostat right now....we are looking at 115v into unit that goes to dooe switch and from door switch to "line" on circuit board.

 

 

Customer: replied 6 years ago.
Ok I have the line H is from door switch not sure wich ground?
Expert:  BillyHvac replied 6 years ago.

Ground can be any metal of the cabinet...

 

 

Customer: replied 6 years ago.
Had to set up heaters and leave. Will try tomorroW.
Will this indicate if power in to switch?
If yes does this indicate power to circuit board?
If no- call the electician?

Expert:  BillyHvac replied 6 years ago.

 

 

If no power to circuit board terminal "Line" then call electrician or furnace man.

If power to Line and no led lit circuit board is bad.

 

 

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