Trane XV90 furnace not lighting

zootjeff

I have an XV90 and it is throwing a two blink error code which says cycle retry exceeded. The inducer blower turns on, the hot surface igniter turns on and then the gas solenoid appears to click, and then the igniter turns off no flame ever ignited, then it cycles a few times, turns on the circ fan and throws the two blink code.

Does this ring a bell? Is the gas valve bad? Do these typically fail? Is there any other sensor that could have gone out that prevents the system from lighting at all?

Gas to the neighboring water heater clearly flows..

jagans

Kill the power, spray all electrical contacts with CRC contact cleaner (All spade lugs and screw connections, especially board ground) loosen screws, spray, tighten screws, wait about a half hour, tap the gas valve a few times lightly. Turn on the power, and try again. No go, come back and Yuri and Doc might happen along. Those guys are top shelf, I'm waste basket.

__________________
" A lot of men build things, and a lot of things fall down "

how

Check that you have house gas (HWT, stove, fireplace)
All supply valves to the furnace are on.
The furnace gas valve toggle is ON.
(We usually manometer the test hole on the downside of the valve.)
*Confirm that the main gas valve is receiving 24V when the hot surface igniter is being energized.
Report back.

zootjeff

OK, so opened up the fire box lid and tried again and it fired right up, then I put the lid back on and it's still running.. Hmm maybe a pressure sensor is getting weak?

zootjeff

How does this thing work anyway? There is a rubber tube on the outlet of the gas valve, then that goes to a tube that just feeds into the firebox, then that goes up to two pressure sensors. What is that system suppose to do? Does it just bleed some gas into the firebox and then some of that gas sets off the pressure switches? Is this a safety thing? Maybe this insures the gas is not too low and not too high?

how

I would have expected that a problem with the PS circuit would have prevented the igniter from being powered.

how

If you have a rubber tube from your "box" to the gas valve then that hose is to adjust the gas valve pressure. You probably have a two step gas valve and ID.

beenthere

You have a sealed combustion burner. the gas valve references the pressure in the sealed burner compartment to control gas pressure. Its a standard method.

Your HSI would not have been energized if the pressure differential switches hadn't sensed enough differential.

Could be the burners are slightly dirty. Does it use outdoor air for combustion, or indoor.

jagans

So its working Now? Filter is clean, You cleaned all the contacts, cleaned the trap etc. and its working? It is not all that hard to take a couple of pictures nowadays, so do it and post them.

__________________
" A lot of men build things, and a lot of things fall down "