3 Flashers "Pressure Switch Stuck Open"

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3 Flashers "Pressure Switch Stuck Open"

Postby southard0410 » Thu Nov 10, 2011 9:30 am

I have a TRANE XE 80. It will not complete ignition cycle.

I am getting 3 flashing lights indicating "Pressure Switch Stuck Open".

I have checked pressure switch with a meter and it tested ok. I tested it with furnace "on" and had 28 volts coming to the switch and traveling thru it to the inducer motor. As I removed the tube to the furnace, the switch would open and stop the 28 volts... reattach tube and switch would close and allow 28 volts to travel thru.

I followed the wire down to the inducer motor and it does get 28 volts. It is not hot. I am pretty sure I hear it running.

The pressure switch is definitely not stuck open, it is closed when "on".

Is this just simply a bad board, giving a bad code?
southard0410
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- 3 Flashers "Pressure Switch Stuck Open"

Postby southard0410 » Fri Nov 11, 2011 1:23 am

28 v to the coil of something. Whatever it is - it is inside the furnace. This is the wire that leaves the pressure switch and does NOT go back up to the controller board.

The pressure switch has an incoming wire from the controller bd.
On the outgoing terminal there are 2 wires, 1 goes back up to the controller bd., and the other goes down to this coil.
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- 3 Flashers "Pressure Switch Stuck Open"

Postby heatseeker » Mon Nov 14, 2011 10:20 am

Call a pro because you are getting in over your head.
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- 3 Flashers "Pressure Switch Stuck Open"

Postby southard0410 » Mon Nov 14, 2011 7:31 pm

I replaced the board and all is well. I didn't need pro service - just advice. In the end I replaced it before I heard back from anyone. I couldn't wait. The board was $150 Service call would be $80 + parts & labor. Gambled (educated guess) and payed off.
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- 3 Flashers "Pressure Switch Stuck Open"

Postby heatseeker » Tue Nov 15, 2011 10:00 am

Very good. maybe you should open your own hvac company with your new found knowledge.
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