"Pressure switch is closed when it should be open"

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  #1  
Old 11-21-11, 08:09 PM
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"Pressure switch is closed when it should be open"

My Tempstar electronic ignition furnace was recently looked at -- it was actually the first time it's been turned on in a year or so because thehouse has been vacant.

The computer was flashing a "pressure switch is closed when it should be open" error. My guy changed out the switch, cleared the flue pipe and the nipple where it connects to the fan.

Now, when I turn up the thermostat, the furnace does not start up at all; just reports the same error. Just yesterday I cleaned out the flue pipe, the tubing and connections. The pressure switch is clicking when i blow on it.

I have been able to manually start the furnace by jostling/disconnecting one of the wires attached to the pressure switch.

Any suggestions? Thanks

 
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Old 11-21-11, 08:20 PM
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My guy changed out the switch, cleared the flue pipe and the nipple where it connects to the fan.
Who is your guy? A trade professional? Get him back to look at it.


I have been able to manually start the furnace by jostling/disconnecting one of the wires attached to the pressure switch.
Would seem to be electrical.


The pressure switch is clicking when i blow on it.
You dont blow in it, youll wreck it. It pulls in by negative pressure. Basically the fan sucks the air from the switch.

What is the model of the computer? And the model furnace?

Mike NJ
 
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Old 11-21-11, 09:06 PM
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Try running a small drill bit through the connector on the fan housing.
 
  #4  
Old 11-23-11, 04:07 PM
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you're supposed to suck on the hose going to the pressure switch to test it. Does the inducer fan motor feel hot after running for a minute or two? Can you verify with a condinuity test across the two metal points on the pressure switch while the inducer fan motor is running? Verify that it is indeed open. It might be closed, but the wires from the pressure switch might not be connected to the board, or not connected in series to the next item. this is extremely rare, but you dont hear water splashing in the inducer fan motor do you?
 
  #5  
Old 11-24-11, 04:35 AM
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the board needs to see the pressure switch open before the ID starts from a heating call from the stat....set the stat to heat then shut the service switch on the side of the furnace...pull 1 wire on the pressure switch put the service switch ON..ID comes ON then reconnect the wire onto the pressure switch.your simulating the PSI from the fan ID proofing out and closing the switch...then the ignition and then the burner...with the unit off and the wires removed are you reading open or closed on that switch
 
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