Gas Furnace, no heat, can smell gas in the crawlspace
Unfortunately, I don't know the model because it was taped over at some point.
It's a gas furnace with electric ignition (no pilot). I removed the programmable thermostat from the wall for repainting, then the house was without electricity for approx 2 months. New tenants moved in and the heat did not work. Replaced batteries in the thermostat and the heat started working.
Couple days later, no heat again. Replaced the air filter, which was very dirty. Here's the current symptoms:
* Thermostat 'Off', Fan 'Auto' -- nothing
* Thermostat 'Off', Fan 'On' -- the system blows air out the vents
* Thermostat 'Heat', Fan 'Auto' -- i can hear noise as if the furnace turns on, but no air flow to the vents
* Thermostat 'Heat', Fan 'On' -- same noise as above, plus cold air blowing
In the crawlspace, I can smell natural gas. So it seems like there is no ignition going on. I'm planning on calling a pro tomorrow, just posting here in the off chance that there is something I could try first.