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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a red blinking light on my Trane XR 80, the furnace

Customer Question

I have a red blinking light on my Trane XR 80
JA: I'll do all I can to help. Tell me a bit more about what's going on so we can help you best.
Customer: the furnace starts up like it's ready to pump heat and then shuts off.. process is repeated 10 seconds later
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. Is there anything else the HVAC Technician should be aware of?
Customer: Not that I know of
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:  airheatman replied 1 year ago.

What is the pattern of the flash? For example. 3 blinks pause or 2 blinks pause. etc?

Customer: replied 1 year ago.
1 blink probably 2 seconds apart from each other
Expert:  airheatman replied 1 year ago.

Ok the single blink is normal.Do you get a different code when it shuts down?

Customer: replied 1 year ago.
It's the same... about a week ago the furnace did the same sort of thing.
Expert:  airheatman replied 1 year ago.

OK you say it acts like it is going to work. Below is the normal sequence.Tell me how far it goes before shutting off.


Thermostat call for heat

R and W thermostat contacts close signaling the control

module to run its self-check routine. After the control

module has verified that the pressure switch contacts are

open and the limit switch(es) contacts are closed, the draft

blower will be energized.

As the induced draft blower comes up to speed, the pressure

switch contacts will close and the ignitor warm up period will

begin. The ignitor will heat for approx. 20 seconds, then the

gas valve is energized to permit gas flow to the burners. The

flame sensor confirms that ignition has been achieved within

the 6 second ignition trial period.

After the flame sensor confirms that ignition has been

achieved, the delay fan ON period (fixed at 45 seconds)

begins timing. After the delay of 45 seconds, the indoor

blower motor will be energized and will continue to run

during the heating cycle.

When the thermostat is satisfied, R and W thermostat

contacts open, the gas valve will close, the flames will

extinguish, and the induced draft blower will be de-energized.

The indoor blower motor will continue to run for the

fan off period (fixed at 100 seconds), then will be de-energized

by the control module.

Customer: replied 1 year ago.
I'd say it shuts off right after the blower is turned on
Expert:  airheatman replied 1 year ago.

OK now normally we should get an error light if a limit or pressure switch opened.

1.Have you cleaned the flame sensor?

2. Des flame change when blower starts?

Customer: replied 1 year ago.
I have no idea how to clean the flame sensor or even where the sensor is
Expert:  airheatman replied 1 year ago.

If you can do some hands on, that is where I would start. Carbon will build up and cause it not to sense flame. I am attaching a generic video that will give you an idea of how to do it.You can clean with a dollar bill or fine sand cloth.

Customer: replied 1 year ago.
unfortunately I don't have the tools required ... will acquire them in the morning
Expert:  airheatman replied 1 year ago.

That is where I would start.Let me know if that solves the problem