My 70s model intertherm fuel oil furnace won't fire up, I have reset it several times, it was firing but only for a short while but nothing now. I cleaned off the cad cell eye... any ideas why?

Fuel system could be dirty. Change nozzle, fuel filter, & pump screen.
Ignition transformer could be weak or dead. Replace
Electrodes could be dirty or out of adjustment. Clean & adjust.
Pump coupling could be stripped or broken. Replace

A lot of possibilities. We need more information. What does it do or what does it not do?

Im thinking its electrical Ive replaces all that you've noted & its getting fuel,the chimney rusted off and fell down in ,Ive since repaired all the sheet metal(an easy fix)I think it may have been putting exhaust gasses into the burn chamber as someone else noted before I fixed the chimney from the top of furnace up. It would fire when I reset it at that time but has not fired since, the reset button does not pop out now to reset it & the thermostat is new & set higher than room temp.. The mod # is as follows The mod# is MAC1265 , it's a 61000 BTU Intertherm oil furnace, in a 70' mobile home.. thanks for your input


Fuel system could be dirty. Change nozzle, fuel filter, & pump screen.
Ignition transformer could be weak or dead. Replace
Electrodes could be dirty or out of adjustment. Clean & adjust.
Pump coupling could be stripped or broken. Replace

A lot of possibilities. We need more information. What does it do or what does it not do?

Today, 09:25 PM
hawgwild61
Im thinking its electrical Ive replaces all that you've noted & its getting fuel,the chimney rusted off and fell down in ,Ive since repaired all the sheet metal(an easy fix)I think it may have been putting exhaust gasses into the burn chamber as someone else noted before I fixed the chimney from the top of furnace up. It would fire when I reset it at that time but has not fired since, the reset button does not pop out now to reset it & the thermostat is new & set higher than room temp.. the mod # is as follows The mod# is MAC1265 , it's a 61000 BTU Intertherm oil furnace, in a 70' mobile home.. thanks for your input

The MAC series Intertherms used a pipe within a pipe for combustion air & exhaust. The exhaust goes out the inner pipe & the combustion air comes down the outter pipe. Both pipes must be sealed to the furnace to prevent recirculation of exhaust into the combustion air.

Do I understand correctly in that the burner will not run at all? Do you have a volt meter & know how to use it?

That's right, the burner will not run at all.. Yes I do have a volt meter

CAUTION: 120 VOLTS
Open the junction box where the wiring from the house connects to the furnace & look for anything obvious. Check for 120v coming in. Follow hot wire to limit switch & check for 120v through limit. Check for 120v between black & white under control with reset button. Reconnect black & white, disconnect orange. Check for 120v from orange to ground or white if you can get a probe under the wire nut. If you havew 120v everywhere except orange, install a jumper between terminals T&T then recheck power out of orange. This will cover most. Get back with us on results.

Ok Thanks ,it may be a week or so this furnace is in our Cabin

Ok Thanks ,it may be a week or so this furnace is in our Cabin
Ended up the primary control was defective & put the right nozzle put back in it ,I had a 60 in It, called for a 57,put a 55 in & it ran fine ,nice & quiet Thanks for all your help Grady It was greatly appreciated.. Have a good day ;)

Glad I was able to be of some help. Stay warm.