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blower fan not coming on and other issues

Posted: Tue Dec 01, 2009 11:51 am
by jackel440
Coleman
model 7975c856
75k btu input
I have been having a few problems with my blower.Sometimes it will kick on for a second or two and then shut off.It does this even when there is no call for heat.It is intermitent.
Now it has a bigger problem.The furnace will call for heat burner comes on,then when the fan should come on it doesn't.Then the upper resetable limit kicks out.I shut it down and let it cool off reset the limit.When this happens the fan is real hotter and actually seems froze up.I have to let it cool some before I can turn the cage.
I have also lost the ability to turn the fan switch from auto to ON and have the fan run.It only works in the auto setting.I will have to get a meter out and do some tracing.
I am afraid I might be having a fan motor on its way out.Looking for anyother reasons for what might be causing these problems so I can repair them.

Re: blower fan not coming on and other issues

Posted: Tue Dec 01, 2009 1:17 pm
by jackel440
I just pulled the fan assembly out.The motor shaft is definatly tighter than it should be.I pulled the motor apart and blew it out.I can see some were on the shaft and bushings.No scoring just wear.I cleaned and packed the bushings with high temp synthetic grease.
Cleaned the whole blower housing and reinstalled.fan now seems to turn more freely than before.I still think I will be looking into a new fan motor.
I will have to see what it does after it heat soaks a few times to see if it will come on like it should instead of just getting hot and freezing up.

Re: blower fan not coming on and other issues

Posted: Wed Dec 02, 2009 5:50 pm
by Robert
Just let me know what it does.




Thanks,
Robert

Re: blower fan not coming on and other issues

Posted: Thu Dec 03, 2009 12:29 am
by jackel440
RObert,
Here's an update on the fan.It still does the come on for a second or two and shut off cycling issue.There seems to be no pattern when it does it either.
As far as it freezing up when the burner kicks on and the furnace get hot,it is working good.No more issues with it freezing up with heat from the furnace so far.
I will have to still figure out why the fan will not work when the fan switch is set to the "ON" position.I also am not sure what is causing the cycling of the fan motor whenever it wants to.
Atleast for now it is working good.

Re: blower fan not coming on and other issues

Posted: Thu Dec 03, 2009 3:53 am
by Robert
Hi,

You'll have to use a meter and wiring diagram and trace test the components in the circuit to see what is opening or closing when it shouldn't.


Thanks,
Robert

Re: blower fan not coming on and other issues

Posted: Thu Dec 03, 2009 10:02 am
by jackel440
Thanks Robert,
Y eah I will have to get my fluke out and run down the wiring to see what i can find out.I hope that maybe i can check into it this weekend to see why its cycles like that everynow then.When I get that done I will update my post.

Re: blower fan not coming on and other issues

Posted: Thu Dec 03, 2009 11:02 am
by Robert
Sounds good, let me know what you find.



Thanks,
Robert