I have a Trane XV80, two-stage HVAC (installed in 1998). I turned on the heat for the first time last week. The burners clicked on and then went out after one second. I played around with it some and got it to try to fire up again by tapping the circuit board. Again, it tried to come on, but gave up after a few attempts. Since then, whenever I turn it on, the fan starts right away with the five-flash error code that "flame sensed with closed gas valve." The AC cycles correctly, but the fan stays on.

I have tried: changing the air filter, replacing an old thermostat that wasn't working properly and cleaning the flame sensor. I've tried unplugging the G wire from the thermostat, but the fan stayed on. I've tried unplugging the flame sensor wire, but the fan stayed on.

About the circuit board: During the summer the unit wasn't cycling correctly. I had the HVAC guy come out. He said all he could do is replace the circuit board. He suggested living with it until it dies. For the rest of the summer, the unit worked fine.

Any additional suggests out there? I'm hoping that it isn't a circuit board issue, because a replacement for this older system seems hard to come by. And I don't want to pay 1/5 the cost of a new system on a board replacement that could only be a bandaid for an aging, failing system.

Thanks for your time and thought!

 

Yes, you have a circuit board that needs to be replaced.

Personally I wouldn't hesitate to replace a circuit board on a 14 year old furnace unless there are significant other issues you haven't mentioned.

 

I have seen leaking Triacs in old thermostats cause boards to fail this way. Just an FYI.

If you post your model number I will provide you with the current replacement control board part number.

 

Thanks for both your advice! I really appreciate your time and realize that it's not like you have to help me! I'm grateful.

HVAC model number is TUD060R9V3H5
Integrated, Variable Speed Control: CNT2223 as listed in the part list. (The actual board says: White Rodgers Emerson 50A51-507)

 

The replacement control board is a KIT

[TABLE]
[TR="class: DataTableResults"]
[TD="colspan: 3"]KIT09370 [/TD]
[/TR]
[TR="class: DataTableResults"]
[TH] Description [/TH]
[TD="colspan: 3"] KIT; RETROFIT KIT FOR CNT02223 , INCL: IGNITOR, IFC PLATFORM, DOOR SWITCH, BRACKET FOR DOOR SWITCH, SCREW, WIRING, HARNESS ADAPTER, TRANSFORMER AND IFC 2-STAGE, V.S. SiNi
[/TD]
[/TR]
[/TABLE]

External Part Note INCLUDES: SiNi IGNITOR - IGN00152, AND INTEGRATED FURNACE CONTROL - CNT03078.

 

Thanks! I picked one up. We'll see how it goes this weekend.

Thanks again, everyone.

 

I installed the kit and it appears to be working fine once again. Thanks, everyone!