mobilehomerepair.com

Greetings,
I recently bought a 1978 854sqft mobile home. Had a friend check the furnace and we discovered it has a counter clockwise motor (had a clockwise motor in it) and we replaced the fan switch as the fan would not cut in for a long period in the heat cycle.
Now that we have that all done the furnace fan does not cut in on warmup for about 4 minutes into the heat cycle and then half way to tempature the fan cuts out. It heats for a while and then fnally the fan cuts back in. We put in the parts according to the parts list. I am stumped.
Do we need a lower fan switch (its a 100/110 in it)
If I recall the model is an 8690.....
Should I just replace the furnace and be done with it?

I'll get the model number for you and the fan switch numbers, etc ASAP - sorry I missed that.

No problem, will need that to know what you should have.



Thanks,
Robert

Model: 7680
Series: 856

80,000btu
64,000btu output

I'll get the rest today

Switch below the transformer:
L15S-2 7680-359
2061L9-718 P3V

Switch above teh transformer:
0934 7710-328
F105-20F 201707 60T82

Transformer:
120V 50 60 C4
BE11246 KIF 45
7660A350
This transformer hums, not sure it that is normal.

Switch at fan:
B3T T.O.T L83 T-O
This one was hard to read and the paper on the back was worn off.

Hope this is all you need sir!
Thank you so much

Make sure the burner tube and burner orifice/spud behind the gas valve are all clean and clear.

Spiders like to build webs in the orifice/spud.


Then if it is still cutting on/off, test across the limit switch to see if it is opening/closing with each off/on sequence.



Thanks,
Robert

OK. Will check the above.
The transformer humming is normal?
Thank you Robert.

Actually if you can link waht I need to buy - I'll replace all the switches.
Even teh transformer as well.

Well I want to repalce the old tired furnace with a new unit - I am looking at a Miller M1MB070ABW A/C Ready. Its a tuch smaller at 70,000 BTU compared to the 1978 Coleman Presidental I have now. I take it would be enough to heat the place? (Sealed cieling tile joints, New windows, doors, etc... but not re-insulated)

so waht I am saying is I want to keep the old one running well until I get a new one installed! LOL

Hi,

You're very welcome. No, transformer humming is usually a sign it is heading out. Some hum longer than others, but I always recommend replacing when it starts to hum.

Make sure all connections are tight and clean and you have correct voltage (120vac primary-line/24vac secondary-load). If so, it should not hum. Keep it though, could be used in an emergency sometime.



Thanks,
Robert

LOL, you kept posting while I was answering, be right back with ordering info.


Thanks,
Robert

Ah sorry must be the black tea I am drinking! LOL

BTW - I redid the connections when I bought the place - they needed a redo.