Tempstar pressure switch question


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Old 10-10-14, 11:56 PM
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Tempstar pressure switch question

Just turned the furnace on for the first time this fall and it starts normal, but the pressure switch keeps cutting the flame out then relighting until it goes into soft lockout mode
The code says "pressure switch stuck open"
The book says "pressure switch circuit still sensed as open 30 seconds after the inducer was energized"

If anyone has any thoughts I would sure appreciate them
 
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Old 10-11-14, 07:59 AM
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I just tried turning the thermostat on and bypassed the pressure switch. The system stayed lite. So I am thinking either the switch is bad ? or there is a loss of vacuum somewhere in the inducer?

The inducer seems to be running normal and I don`t believe there could be any obstruction in the exhaust vent (although I have not disassembled it yet).

What other conditions could cause a loss of vacuum in the inducer?

I don`t have a way to test the vacuum other than an automotive vacuum gauge witch is messured in (inches of vac)
 
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Old 10-11-14, 08:22 AM
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I suggest you remove the hose from the inducer motor port where the hose from the pressure switch attaches. This port gets restricted with crud and can cause issues such as yours. You can use a small drill bit or an opened paper clip to ream it out. Make sure the port is clear throughout. Also make sure the ends of the hose are clear.
 
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Old 10-11-14, 10:58 AM
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Nice call! The pressure switch had some crud deposited where the hose attaches. Cleaned it out with a paper clip. Problem solved..

Thanks!
 
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Old 10-11-14, 11:05 AM
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Glad to hear you resolved the issue and thanks for the update as it will help others with similar issues. It is a good idea to clean out that port at least annually while performing preventive maintenance.
 
 

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