I have a Trane xl80 two stage furnace, vent motor starts and runs ok but the ignitor will not come on and then vent motor shuts of for about 5 sec and re-starts then the ignitor starts to glow and gas comes on and every things runs ok, this happens about approximately two times a day. also gas and blower will shut off before getting to room temperature. These two problems are intermentely taking place. can any one help

 

It sounds like there may be an issue in the exhaust system. There is a pressure switch that monitors the exhaust pressure.

In the front of the blower door should be a sight glass. After furnace shuts down you should see a flashing LED(s). Those blinks will signify a trouble code. Post them here.

 

This problem has happened several time and there were no trouble codes. Today, the vent motor started, the igniter did not come on, the timer for the vent motor timed out and started a second time and the igniter glowed and the gas came on and all worked ok. I have been told that it is a circuit board problem maybe a burnt relay on the board or a intermiten igniter problem. Can any one give me any input ?

 

In order to determine if it was an actual ignitor problem..... you would have a voltmeter set to just over 120 vac connected to ignitor lines to see whether or not the voltage was actually present.

 

Thanks for the reply PJmax
It is hard to catch when the igniter fails to check for the present of 120 volts. I did check continuity on the igniter and it checked out ok. I went one step futrher I replaced the igniter and the first time the furnace kicked on it worked ok, the second time the vent motor came on timed out came on again and the igniter worked ok and has worked ok since 9:00 PM. Could it possable be a bad solder joint that is loosing contact and again, a bunt relay on the board ? Trane has changed the control board for some reason the part # went from a D341418P01 to a D344426P01 which comes in a Kit # KIT15943. I Posted another problem earlier on the same furnace, which I still have this problem, while the furnace is running, gas and furnace blower that pushes the heated air into the house is on, both gas flame and blower will go off at the same time which does not allow a cool down time for the heat exchanger this happened also this morning, could these two problems be connected.

 

There should be a small hose leading from the inducer motor to a pressure switch. Pull the hose and make sure that it and the nipple on the motor are clear. If you gently suck on the hose, you should hear the pressure switch click. No click - check pressure switch.
The inducer motor pulls a slight vacuum when running properly which turns on the pressure switch and allows the next stage - HSI - to operate.

 

Thanks goldstar for your reply

Before I read your response, I was looking everything in the furmane again and checked the small rubber hose that you are refering to for any thing that might be blocking the hose, when I took the hose off of the small nipple that connected to the furnace it fell off the vac switch nipple, what may have been happening was that the hose was leaking and not holding a vacume which may have cause both problems. Will keep every one informed on the out come.

 

About your main blower issue...... make sure your thermostat is set for a gas furnace and not electric. Also.....the blower shut off after a heating cycle is controlled directly from the control board.

 

Thanks PJmax
Sadly to say I still have the problems. I have another question, Is it possable that the control board could have a problem and not set a code ?

 

You should upgrade to the new board. I believe you have a control board logic issue. The reason that Trane came out with the upgrade KIT15943 is to change the ignitor to 120V from 80V. They were having failures with the old 80V system.

 

Thanks hvactechfw for your reply

I had allready came to that conclusion, I had already purchased the kit # 15943 about a week ago, I was trying to totally rule out every possable reason I was having these problems but gave up. My son and I installed the new board and ignitor Saturday night which took about 1-1/2 hours to switch out and every thing has been working great since then. I did post a question about the fault code light whether it was possable for the board to have some thing wrong with it and still not show a flashing code, the old board that I switched out never did set a trouble code so it is possable for a board to be bad and not set a trouble code. I am greatfull for every one's responded to my post and through the thing that I found out hopefully it will help some one else out. Thanks again.

 

yes, a bad logic in the board could produce that type of condition.

 

plant4250,
Since you have recently upgraded your Trane XL80 I have a simple question for you:
I have my KIT15943 all installed but the connections for the 3 neutral wires was not very clear in the instructions and comparing the connectors labels on the old and new board did not help.

Can those three neutral wires go on any of the 5(?) neutral connectors on the new board?
At first I figured neutral is neutral but then I looked at the wiring diagram on the old and new and I decided to hold off rather then toasting the board.
Thanks.
David

 

Welcome to the forums.

On that board....... all five neutral terminals are connected together so you can connect your neutral wires in any order.