Hello, I have problems with my Furnace. I currently have a Lennox G12RD2-82-3 from 1980. Last week I replaced the furnace blower but now the furnace won't ignite. These are the conditions:
--the pilot is always on
-- I have replaced the thermocouple
--the thermostat is OK
--the blower kicks on after a while even though there is no fire.
--when I changed the thermocouple it only ignited for a few minutes then
Went back to pilot mode.
--the wires seemed to be OK
--the house switches are all on and there is current.

Please help, the tech's charge too much and I am very desperate. I am getting cold.

Is there 24 volts to the gas valve when the thermostat calls for heat?