Lennox furnace not working

[signcrafter]

Have a lennox surelight that has been working fine and came home tonight and thermostat was blank and no heat. When I open up the furnace both green LEDs are flashing slowly which means operating normally according to the chart. The thermostat is a honeywell home digital wifi that I put in a few years ago. Thinking because the LEDs on furnace are saying normal and thermostat has no display that the thermostat is dead. The thermostat has no batteries. The only other thing is there is an amber or orange LED that says hi/lo by it that is on solid, not sure if that is normal or not? Is there a way to "jump" the thermostat wires to get the furnace to turn on so I can test if it is the thermostat or not? Going to bed for the night and hoping I don't wake up as an icicle. I did turn the shop heater on and opened the door so it's staying around 55 degrees for the night so should be fine. Planning on running to town in the morning to get a new thermostat unless someone posts different on here tonight. Thanks.

 

[PoorUB]

Look where the thermostat wires are connected inside the furnace. You should find 5 or 6 connetions, but jumper the R to the W terminal and the furnace should run constantly if it is a problem with the thermostat or wiring to the thermostat. There are safety switches so the furnace will not run with the panel removed. if it still doesn't run, you have other problems.

 

[signcrafter]

Look where the thermostat wires are connected inside the furnace. You should find 5 or 6 connetions, but jumper the R to the W terminal and the furnace should run constantly if it is a problem with the thermostat or wiring to the thermostat. There are safety switches so the furnace will not run with the panel removed. if it still doesn't run, you have other problems.

After I posted this I googled how to jump the thermostat and did exactly what you said and furnace fired right up. So letting it warm the house up to 72 or so and will shut it off and call it a night. Will get up at 5 and run to town and get a new thermostat and should be good to go. Thank you for the quick reply.

 

[Jim greengo]

I'd run it up to around 75 atleast if it was me,Temps can drop fast with no heat at night.
Leave the wires jumped,then just shut switch off on side of furnace.
Makes it easier to kick heat up in middle of the night when it gets cold.
Put a plain old non programable/non wi fi thermostat back on there you'll be much happier.

 

[PoorUB]

After I posted this I googled how to jump the thermostat and did exactly what you said and furnace fired right up. So letting it warm the house up to 72 or so and will shut it off and call it a night. Will get up at 5 and run to town and get a new thermostat and should be good to go. Thank you for the quick reply.

If you have a voltmeter, pull the thermostat off the wall and check for voltage from the R to C terminal, or R and any other terminal, (with the jumper removed!) and it should show 24-26 volts. If it doesn't you might have a broken thermostat wire.

 

[signcrafter]

I'd run it up to around 75 atleast if it was me,Temps can drop fast with no heat at night.
Leave the wires jumped,then just shut switch off on side of furnace.
Makes it easier to kick heat up in middle of the night when it gets cold.
Put a plain old non programable/non wi fi thermostat back on there you'll be must happier.

I will run up to 75 then. I like sleeping in the cold so that isn't a huge issue for me, just don't want pipes to freeze but it's only getting down to 30 tonight so that shouldn't be an issue. We liked the wifi because we used to be gone often and could check or change temps while away. If I was gone and this happened I could check temps from my phone. But we are selling this house so I will pick up a plain old thermo for here and call it good. Thanks again for the help.

 

[signcrafter]

If you have a voltmeter, pull the thermostat off the wall and check for voltage from the R to C terminal, or R and any other terminal, (with the jumper removed!) and it should show 24-26 volts. If it doesn't you might have a broken thermostat wire.

26.8

 

[PoorUB]

26.8

More than likely a bad thermostat.

Remove the jumper from the furnace and jumper R to W at the thermostat and see it is runs. Is yes, replace the 'stat.

 

[signcrafter]

More than likely a bad thermostat.

Remove the jumper from the furnace and jumper R to W at the thermostat and see it is runs. Is yes, replace the 'stat.

I did remove wires at thermostat and jumped it there. Figured that was easier to do with aligator clip jumper wire then at the furnace. Plus furnace has safety switch when cover is off which needs to be off to get to control board. So I just went to thermostat wires from start. Will get thermostat in morning. Thanks for the help.

 

[signcrafter]

Drove the 30 miles in a snow storm to box store and got a new thermostat and all is good now. Thanks for the help, learned a few things in the process.