Trying to trouble shoot a furnace for a friend before it gets too cold up here in Alberta... It's a old Lennox G8D2-82-3. The furnace will not turn on no matter how high you turn the thermostat..I've taken a look at the thermocouple and it looks absolutely coated. I'm pretty sure this is the problem, however, the pilot light is on continuously so I can't get in there to clean it...I've cleaned the thermocouple on my furnace before but it is relatively new and only uses a glow igntion (or whatever it's called....sorry)...never one that has a pilot light on all the time... Do I have to shut the gas off on the line manually and let the system cool down before I access the thermocouple or is there another way to get to it? Thanks for the help!