Lennox G26Q3-75-5 with both LEDs off; no heat

[chrisny]

Our Lennox gas furnace was serviced less than 1 week ago, and in addition to 20-pt. annual maintenance they installed a whole house humidifier unit. Furnace worked fine for about 5 days, then all of a sudden no heat yesterday. Before looking more closely at the furnace I thought it might be a new thermostat that was needed, so I installed a new 3M Filtrete touchpad unit upstairs in the kitchen. Nice thermostat, but STILL NO HEAT. So I go down to take a closer look at furnace, and I see both diagnostic LEDs are OFF, and there is no sign of any current whatsoever reaching the furnace. Furnace switch is on; circuit breaker on home service panel is ON. I even pressed the internal circuit breaker on the furnace control box a few times. Still no heat, no flame, and no sign of current reaching the furnace control box. Could it be that I need to replace the CB8 circuit breaker, or is something else going on? PLEASE HELP!

[chrisny]

P.S. -- I realize the installation of th humidifier is probably an irrelevant factoid, but I feel kind of suspicious that the serviceman screwed something up while doing the annual maintenance, like loosening a wire perhaps -- thhough everything SEEMs to be in place. Thanks a million for any ideas!

[RegUS_PatOff]

Is the Access Door closed on the Furnace ?

The Circuit Breaker CB8 is re-settable.

Inside the Control Box:

(with Door Switch closed)

there should be 24v AC between C and R

there should be 120v AC between Terminals L1 and N

[chrisny]

Thanks for the quick followup, GMF. The access door is of course closed when I am testing to see if the thing works. I have actually reset the CB several times, to no avail. The CB reset button seems somewhat loose and flimsy; don't know if it was always that way.

Unfortunately I have no way of testing voltages. Hopefully I'll have a guy coming over tomorrow or after -- so, we'll see, I guess. Thanks anyway, though.