Hi all, I have a Lennox 90UGF Series Unit and it is not starting up. I raise the thermostat temp a couple of degrees, and I can hear "something" turning on (sounds like either the fan or it's simply getting power) but I don't hear that "whosh" sound, even after it's been turned on for a while. Now, I did neglect the air filter for a few months (totally forgot about it) and when I replaced it yesterday, the old one was pretty dark with dust.
Hope someone can help.
Rob