I have a Lennox pulse furnace I recently replaced my thermostat, air conditioner works fine but furnace will not kick on, I hear it click on at the thermostat and furnace, but heat will not come on. Would the problem be the thermostat or the furnace?

If it is a Lennox Pulse furnace I would have it checked by a professional that is well versed in that brand and model.From your description I am sure the problem is in the furnace and you need to find someone who really knows the Pulse furnace to check it out and repair it or replace it before the winter.

Agree, sounds like furnace problem. The pulse is whole different breed of furnace, takes special training to really get to know these monters.. Definitely have a pro in to check system.

Sound advice,, I`ll add one item,when you replace it,, buy something other than a Lennox

I agree with all the above. Make sure the tech you hire is lennox trained and know these units. Make sure you mention the type of furnace when you call for service.