Furnace troubleshooting help

charliechicago

Hello to all,
I have a 15 year old Luxaire furnace and the board is giving 5 blinks which means rollout switch open or rollout situation. The problem is all the rollout switches which are all manual reset are closed and all I have to do to get the heat working is to turn power on and off. Could it be a rollout switch issue or the board or something else?
Thanks in advance, Charlie.

HVACNUT

If there is rollout or the flames aren't being pulled into the tubes properly, turn the furnace off.

You've checked the rollouts with a meter or the buttons dont click?
Turning off 120v then turning on again will make it work?
Does it run the whole cycle?
Check the chimney and induced draft assembly.
I had one last Thursday where a Blue Jay was jammed between the IDM housing and fan wheel.
The furnace would run for a while then open on a pressure switch but I can just as well see your status light showing rollout.
Sometimes those codes are false accusers. It's not telling you a rollout is at fault, its telling you to check the whole control circuit in which the rollouts are in series with.

Or it could be the board.

If you have a meter, you can continue to troubleshoot with the gas turned off to a certain extent.

GBart

Sometimes there is a limit in the row with the roll outs, if the roll outs aren't tripped and need a manual reset this could be the case, could be an airflow issue, dirty filter, vents closed or blocked, etc. Checking the wiring diagram would confirm this.

JUGHNE

Some furnaces put limits on either side of the air blower motor, (in the event the unit was used horizontally), they should not have tripped but could have loose connections. Follow the limit wiring. FWIW

ratio

Also, sometimes the connections to the limits will go high-impedance—looks like rust or corrosion to the layman—pulling the connectors off & putting them back on a few times may get it going for a while. Best to find out what's causing it though.

DZoro

Check your condensate trap, if it is the black one make sure all the ports are clear, can easily blow through. Not sure if that model has a limit inside the burner box?

charliechicago

Thank you to all,
I will look at the connections. I dont think its a limit issue because when i pulled off the wire for the limit it gave me a different fault code. The unit vents through the roof and the flue piping is fine. It can run for days with no issue. Is it possible it can open but non pop the manual reset?

DZoro

Clean the condensate trap box. Very possible it's slowly draining during shut downs, which would clear its self when you reset. But can't keep up draining during the run cycle. Good chance it is the board if that is the original board. Just would like to see simple maintenance done before major repair purchases. Has the filter been well maintained over the last 15 years? Animals in the home?

SuperTech

I have seen some furnaces that have a pressure switch in series with the rollout switch. Also sometimes if a furnace is converted for propane usage the low gas pressure switch will be wired in with the rollout switch. Is your furnace natural gas or LP? Can you check the wiring diagram and see if anything else is wired in series with the rollout switch?
I haven't encountered a rollout switch problem with a switch that didn't trip.
It could be a board but it other things need to be checked first.