Very old Tempstar furnace and ac, blower intermittent


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Old 06-29-14, 05:48 PM
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Very old Tempstar furnace and ac, blower intermittent

Once last summer the ac outside turned on but the furnace blower did not.
I played with the switch which senses the front panel. It has run a couple of weeks this year until this weekend when it acted up again.
playing with the switch has got it working again but I would like to know what might be causing this .
I cant get in to the heat exchanger inside the furnace as it is a sheet metal housing but it appears to be working fine.
Am I looking for a dirty switch or bad sensor or something else?
any help would be appreciated thanks.
 
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Old 06-29-14, 07:21 PM
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Welcome to the forums.

Thanks for starting a new thread.

That switch on the front of the blower door is a safety switch. That is there so that you can't stick your hand in the blower fan while the door is open. When the door is open..... nothing in the system will work. The outside unit won't work with door open either. So your problem is not the safety switch on the blower door.

You're telling us the furnace is old. It may be time for a new furnace or at this time at least a blower motor.
 
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Old 06-29-14, 08:25 PM
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That goes without saying but I don't have money to replace unless I have to.
I know the switch at the front is a safety switch and I know it probably is not the problem as the hot air worked all winter, but it might be dirty or wore .
I am not a beginner at electrical or trouble shooting things, I was hoping for some Information on possible sensors or switches or even circuits in side that might cause this sort of problem.
Thanks for the reply though.
 
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Old 06-29-14, 10:58 PM
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It's possible the switch could be going bad. You could verify that with an ohmmeter.
There should be a relay in the furnace that controls the blower.

There should be a wiring diagram on the back of the blower door that will diagram the system.
Otherwise I'd need a model number to help you further.
 
 

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