1980s intertherm furnace cycling on and off

nick1

I have a 1980s home with an intertherm propane furnace in it, the blower cycles on and off continuously while the burner is still on.
I replaced the one button style limit switch already and that did not help, I am left to believe it is the remaining limit/fan combo switch which is no longer made unfortunately. I tracked down the best recommended replacement part which is a camstat FAL3C-05TD-120-A. This part has only 4 spots for wires, and the old switch has 5 wires coming from it. 40tn33113 is the old part number, and I cant seem to get photos to load. I am a mechanical engineer, but cannot figure this out and have already had the only service guy out here that comes up this way. I live in the mountains of CO, nobody serves my area. We are getting cold up here, so any help is very appreciated.

nick1

the old part is also referred to by thermodisc part number 6261854
https://www.aberdeenhomerepair.com/store/f135-l130-fan-limit-combo-626185-nla-p3370.php


and here is a link to the new, replacement part https://nativesupplycompany.com/FAL3C05TD120A-fan-limit-control-3-inch

JUGHNE

Is this a counterflow furnace? (Blows the hot air down).

Just to get you working you could turn the t-stat fan switch to constant "on". Delivers cooler air but should heat you temp.
If no t-stat fan switch then jumper R to G on lo voltage terminal strip and fan should run continuously.

If this temp fix becomes long term you should pick a lower blower speed. Info should be on wiring diagram.