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Kenton Guidry
Kenton Guidry, HVAC Technician
Category: HVAC
Satisfied Customers: 966
Experience:  12 years install/service experience.
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Furnace light keeps blinking with no heat. What to do?

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My Trane XV80 furnace light keeps blinking, and there is no heat coming out of the furnace and everything is quiet.

I would like for you to do something for me.

There is a reference for what the blinking light means.

You will have to count how many times the light blinks.

Then look up what the code means on the panel of your furnace.

The code may be on the inside of the panels.
Customer: replied 8 years ago.
I followed your instructions and counted the number of blinks, it is one continuous blinking, like heartbeats. Normally, it would blink very slowly, but now it is blinking continuously like heartbeats
Does the blinking stop, then start over?
Customer: replied 8 years ago.

No, doesnt stop at all. After I followed yoru isntructions and gave you my last reply, I put back the control panel, and it seems that the light is now blinking faster.

I see.

I would like you to do something for me.

Turn the power off for one minute.

Then turn the power back on with the heat on.

Watch the furnace.

Tell me what sequence of events that you see and where the furnace stops trying to heat.
Customer: replied 8 years ago.
I followed your instructions in turning the power off for a minute, I did so for two minutes and then turned the power on, and nothing happens!!! The light still blinks continuously and the furnace did not light up with flames.
Is your thermostat set for heating with the temperature turned up enough?
Customer: replied 8 years ago.
that was one of the first things I made sure of, and I have already set my thermostat for 75 degrees!! and still nothing!
If I were to ask you to jump the terminals on the thermostat base, would you know how to do it?
Customer: replied 8 years ago.
I think so because I have installed this new thermostat several months ago and it worked fine until now. Let's give it a try! Just give me some clear directions, smile!
Sounds good.

To jump a thermostat, you will need a piece of wire.

I use alligator clips with a wire between them as my jumper.

I would like for you to Jump the R terminal to the G terminal.

To access the terminals you will need to remove the thermostat cover.

Please respond with any questions you may have on this process.
Customer: replied 8 years ago.
I see that my wires are attached to W terminal and RH terminal. what do you suggest? completely change the wiring?
Take a piece of wire and touch one end to the r terminal, and touch the other end to the g terminal.

Your indoor fan should come on when you do this.
Customer: replied 8 years ago.
I see RH and RC terminal, no R terminal.
Is there a jumper installed that connects the rc and rh together?
Customer: replied 8 years ago.
there is a jumper for both rc and rh in place.
That is your 24 volt power.

What you will be doing is placing the wire on the power (rc, or rh) to what ever terminal we are testing.
Customer: replied 8 years ago.
Ok, the wire is on RH, that's for sure. You want me to test the wire connecting RH to G?
Correct, but do not remove the wires from where they are. Find another piece of wire in your home and perform the test.
Customer: replied 8 years ago.
i got it clear. In fact, i have this spare wire ready for the test, Ill go do it now.
Your indoor fan should come on when you touch the wire.
Customer: replied 8 years ago.
I tried to jump twice and nothign happened. the switch for the fan is in "auto" position. Should I switch it to "on" position?
Take the cover for the thermostat off and leave it off.

Then touch the wires.
Customer: replied 8 years ago.
I put the wire inside RH terminal and inside G terminal, and nothing is happening!! HELP!!!
For some reason you are not getting your 24 volts to your thermostat.

Since you have the blinking light I believe that your transformer is still good.

You may have a blown fuse. If you have a fuse ,it would be located in series of the transformer(at the furnace).

Otherwise you will have to use an electrical meter to diagnose the problem.
Customer: replied 8 years ago.
Or possibly the thermostat is blown??

The test we did was to see if the thermostat was your problem.

What you did was what the thermostat does, which is to take 24 volt power and apply it to certain terminals.
Kenton Guidry and 2 other HVAC Specialists are ready to help you
Customer: replied 8 years ago.

Ahh, I see!!! So this test was to rule out the thermostat, then... ok, I will call in a HVAC technician tomorrow or Monday then... Ok, many many thanks!!!!

You are very welcome.

I looked on the Trane website and the furnace has a 5 year warranty.