Originally Posted by Tk0608
So for a few years I've. Had my furnace having issues initially I thought it was all because of a bad tstat with bad switches but finally after a nightmare replacing with up to date stat and control unit sadly it still doesn't want to fire up unless I put a portable heater in front of the intake. And run it hot for a few and reset the heater a few times till it fires but it absolutely refuses to ignite while cold. And well winter is a nasty season here I need my heater to be reliable any help or tips would be greatly appreciated
Sounds like a sail switch. When colder, the fan motor turns harder and since you say this has been going on a few years, you might be right at the threshold of where it blows hard enough when warm but not when cold.
Do you hear any noise. I had one that when on shore power would light and run fine, but on battery alone would not. Fan ran just fine. Took it apart and it had the plastic squirrel cage fan with one blade broken out. On shore power, full 13.6 volts ran fast enough to trip the sail switch. On battery, not quite.