XR80 Trane (2 red flashy lights error code)

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Old 01-17-16, 10:32 AM
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XR80 Trane (2 red flashy lights error code)

Hey guys,

Of course this would happen right in the middle of winter when it's 30-40 F degrees outside. Ok so, like other Trane owners of the same model, I noticed that my vents were blowing cool air while my t-stat was in auto heat.

I've read some other forums with people having the same issues and followed their diagnostic steps.

I have discovered that my glow plugs will light up for 10-15 seconds, BUT my gas valve doesn't do anything. (no solenoid clicking inside to open valve)

I've read that the two tabs connected to the gas valve (read and blue wires) should be getting 24 volts ac. This is where I am needing guidance. I am not expert with a multimeter. I selected V~ which I believe is Volts AC. There are numbers that you can select on the dial. I selected 2.

I connected the read lead to the red wire on the gas control valve and the black lead to the blue wire. The meter is displaying roughly .50 -. 60. I think it flucutates when the glow plug comes on which is when the gas valve should be opening. I read that I should be getting 24 volts so I don't know if I am doing this test wrong or I am having another issue.

I followed the red and blue wires back to the control board. These wires connect going into a socket connector attached to the control board. This same connector has another blue and red wire that goes to a different module. This module has a black and white wire connected to it. I think it may be a transformer.

Long story short, it seems like my gas control valve may not be getting the necessary 24 volts to operate, but I don't don't if it's a control board issue or that transformer. Ill post a pic of the control board with red and blue wires.

I'm not sure what to test next. I would really appreciate some help. Got a baby due in couple weeks and will definitely need a warm house!
 
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  #2  
Old 01-17-16, 10:48 AM
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Welcome to the forums.

A 2 flash fault is lockout. You need to turn power off to the furnace, wait ten seconds and power back up.

You need to describe exactly what happens and what fault code you get.

FOR EXAMPLE......
Call for heat.
Inducer starts running.
15 seconds later igniter starts glowing.
30 seconds later you hear a click, the igniter turns off, a code comes up.
 
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Old 01-17-16, 11:19 AM
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Hey PJmax,

It's good to hear from. I've read some of your other post which have been really helpful.

Yes I saw that the 2 red lights mean an external lockout. I was wondering if I had to do the hard reset procedure. (turning it off, on, off, and on with a 30 second period).

Let me try to explain better.

I'll select auto heat from the t-stat. The red light seems to blink rapidly in a continuous pattern which I believe is the call for heat. (normal operation)

Within a short time period (maybe 30 seconds) a small fan that has a vent connected to it that leads to the outside of the house starts running. Is this the inducer? After a few more seconds the glow plug for the furnace lights up and stays on about 10-15 seconds. During this time nothing changes. The gas valve never seems to open. After another 15-30 seconds, the glow plug comes back on while the inducer continues to run. The glow plugs goes off after the same amount of time. This process repeats maybe one more time.

The main fan blower eventually comes on and that's when I can feel non-warm air coming out of vent. That's when I notice the 2 flash error code. I am not exactly sure when the error codes starts since I was watching the furnance.

My main problem is that the gas valve is not receiving 24 colts. My display says .50-60 volts ac?
There is a 115 volt transformer next to the control panel. It takes 115 volts and turns it into 24 volts. Then it passes through the control board and than heads to the gas valve.

I'm going to go test out the transformer now.
 
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Old 01-17-16, 11:25 AM
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If the board is working.....and it is.... the transformer is good. The board runs on 24vac.
That little motor is the inducer.

Probably going to need the full model number here.

The igniter should glow continously for usually 30 seconds...... then you should hear the click of the gas valve relay and the igniter shuts off. The gas valve will only have 24v on it for a few seconds. Those few seconds occur just before the igniter turns off.

So the best thing to do is to clip the meter on to the two wires going to the gas valve. Watch the meter as the cycle proceeds. If the meter never reads 24v before the igniter shuts off then the board is defective.
 
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Old 01-17-16, 12:45 PM
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Fixed

Thanks PJ. I knew that my gas valve wasn't receiving 24 volts so I tested all of the sensors and made sure they were good.

I tested out the transformer and it was putting out 27 bolts so that's good (red & blue wires) They go into the control board. I tested the other red and blue wires that are connected to the control board and lead to the gas valve. They weren't showing any power so I thought hmmm control board is acting up. Than I realized that one of the wires didn't seem to be properly seated in the socket. My guess is had backed out over time. Maybe due to vibration from the air handler fan over time. Anyway, I pushed it down so it wsa connected to the control board and ran another cycle.

The furnace came on and I'm back in business. I hope my lil story can help others running the same old 1980's gas furnace. Somehow I just don'e feel like spending 6k on a new unit..
 
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