Hello

My furnace has been acting up lately. The thermostat will call for heat and I hear the furnace trying to start up but is not blowing any hot air. After 15-20 secs it shuts down, waits for about 2 minutes and does the same thing. Then I switch it off and wait for 30 minutes or so. When I turn it back on it starts working fine. I works well for 2-3 days and does the same thing again. And when I open the cover to see for error codes, the small hole, through which I would normally see a green or amber light flashing, has no flashing or solid light at all.

How do I fix this?