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1980s intertherm furnace cycling on and off
nick1
Member Posts: 2
in Gas Heating
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.
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.
0
Comments
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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-inch0 -
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.0
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