I HAVE A TRANE XR80 FURNACE I AM HAVING A PROBLEM WITH. IT…

December 30, 2011

Question:

I have a Trane XR80 furnace I am having a problem with. It started with the igniter not staying on to open the gas valve. We replaced the control board with a universal ignition control module board. We also replaced the gas valve. The burner will now ignite but only for a few seconds. I replaced the flame sensor. It did the same thing. The only thing I have not is the igniter or pressure switch. Would appreciate some help. Thanks, XXXXX XXXXX

Answer:


servtech50 :

Hello and welcome to Just Answer. I am servtech50 and will assist you today.

servtech50 :

I am assuming the universal control was for your Trane furnace.

servtech50 :

the igniter does not open the gas valve it is only on during the first call for heat

servtech50 :

what opens the gas valve for flame is the proof that the pressure switch was opened then closed when the call for heat came to board

It was for a trane furnace. pressure switch will open up to turn the igniter on and the burner will ignite for a few seconds. Just can’t keep the burner going.

If I understand right, it seems the pressure switch might be the problem.

servtech50 :

the pressure switch should be opened when there is no call for heat. closes after the ventor motor startes up. proves to the board the ventor is running the the glow coil turns on and a few seconds later the gas valve opens to start flame. The question is does the pressure switch open after the flame starts???

servtech50 :

if you would just to elliminate possibilites, pull thermostat from wall and jumper “R’ to “W”. or at the furnace with no call from thermostat jumper “R” to “W” and see if furnace continues to operate.

I will have to go test that and see if it opens during ignition. I tried a jumper wire this morning and the burner still cut out. I will try to test the pressure switch to see if I lose power on one side.

servtech50 :

where did you try the jumper?

We also put a new thermostat in also. We tried the jumper at the furnace.

servtech50 :

have you checked the hoses that go to the pressure switch to see if any obstruction in hose or either orifice (either end)?

servtech50 :

of pressure swithch

servtech50 :

switch

I blew in the from the presure switch the the inducer motor. it was clear

servtech50 :

ok. what you can do now is remove both wires from the pressure switch (with no call for heat), after wires are removed start a call for heat. wait about 5 seconds then connect the two wires together and see if furnace continues to operate.

I will try that tomorrow and see if that will go. Will let you know if it works. Thanks for your help.

servtech50 :

you are welcome. but if that does work it could be either the pressure switch or a weak ventor. and the only way to check that would be if you had a magnehelic gauge to check low pressure. If not it will be trial y error. replace pressure switch and if that does not do it then the ventor.

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