I need a wiring diagram, etc. especially an installation/maintenance manual, for a Janitrol M-120 gas furnace. I am specifically interested in knowing the connections for the manifold high-limit temperature switch and the fan motor relay/contactor.

Schematic is usually found on the inside door of the air handler.

Thanks for your answer but the diagram is missing. This furnace, Janitrol by Moffat, model M-120, S# 039991, was supposedly installed in 1968 when the house was built. Over the years various people have worked on the furnace and changed the wiring around. I had to rewire it to the Air conditioner contactor, gas valve and thermostat. One connection I need to make is the high temperature limit switch to the primary of the control transformer to enable it to shut off power if the heat exchanger or plenum temperature is too high. I don't know where that switch and wires are physically located on this furnace, I need to know that information. The color of the wires that go to the high temperature limit switch would be useful too.

On my last two furnaces, a Day and Night and an Amana, the limit switches were located on the left side of the plenum, about 2-3 inches above the burners. Small round disc with 2 wires. I have seen others that are square or rectangular. All of them have 2 wires. Some are thermal snap discs that reset.