Gas and Oil Home Heating Furnaces - Fan Starter Switch

I have a 1955 Lennox oil furnace (# OHR4D-65-M). Sometimes the fan does not shut off and blows cool air until someone bangs on the front of the "Make up box" (their name) with their fist. I have determined that the switch inside is sticking and can sometimes make it work correctly for a while by taking it out and cleaning it with WD-40 however this at best only works for a few days. I would like to replace the switch but don't seem to be able to find it by searching the internet parts places. The wiring diagram calls it a "Fan Starter Switch" it has WA-2C-A2 stamped on it. Does anyone know if this switch is still available or if there is a replacement for it and where I might find one? Thanks!

The most popular model I see is the Honeywell L4064 (I think). It is a combination fan and high limit switch. Yours probably does both also. The only thing you need to know before picking one up is how long the helix (probe) is on the one you have now. There are a few different lengths available and you should match what you have to sense temperature in the proper location. 5 and 11" are the two popular lengths and there are others that OEMs use. The wiring will be very similar to what you have now but you may need to replace some of those 40+ year old wires if the insulation all breaks off when you disconnect it. Post back with any other questions.

if low voltage limit is used, be sure to cut the jumper. it will be in the instructions.

I took a closer look at this switch. It's not a limit switch with a probe but is called a "time delay relay" it was manufactured by DETRO CONTROLS and has "CA 850 stamped on it. It has a wire coil on the side and a "MICRO" switch mounted on top. The unit is made of black plastic and can be separated from the switch on top. I've tried searching some of the online parts places with this new info but am still drawing a blank. Perhaps it has been superceded by different unit but I have no way of cross referencing. Thanks for any help!