Started my YORK heater the other day and ran into a problem that I can't figure out. When the controls at the t-stat are: heat ON and fan to AUTO heater kicks on, yet the huge fan at the bottom of the unit will not kick on, everything shuts down, and I get 4 red flashes which means "open limit" on my board. Now, I shut down heater reset settings to the same as above and when heater kicks on I reach down into the motor and spin the shaft she goes without any problems and will run for days. Now here is the tricky question. When I just simply put the fan to the ON position and the HEAT to the OFF position she kicks on and will run forever. This is an older heater possibly 12-14 years old. Model #p2mpd12no6401a. Thought maybe the motor needed to be oiled, yet owners manual said that this motor is sealed and does not require oil. Maybe capisator? $$ is tight and I don't want to go out and just buy things that are not going to work. Any information would be great, hope to hear something soon. Thanks in advance.