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Kenton Guidry
Kenton Guidry, HVAC Technician
Category: HVAC
Satisfied Customers: 966
Experience:  12 years install/service experience.
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I have a Trane XR80 furnace. Error code is flashing 3 times

Customer Question

I have a Trane XR80 furnace. Error code is flashing 3 times: Problem w/ pressure switch. I have tested the switch with voltmeter, the circuit closes when the forced draft blower starts. I have tested the switch wiring for continuity- no ploblems found. 24 volts present in circuit.

All other furnace functions appear to be fine, but unit does not light. What is the next troubleshooting step?
Submitted: 7 years ago.
Category: HVAC
Expert:  Kenton Guidry replied 7 years ago.
Try jumping the switch when the id fan comes on.

If you still get the pressure switch error, look to see if the wiring in series of the pressure switch has any trouble areas.

Some systems have other safeties wired in series to the pressure switch.

Please let me know what you find.

If we discover that the pressure switch is working properly and you are getting a reading through the switch back to the control board, then the board is the problem.
Customer: replied 7 years ago.

There is 24 V in the circuit. I will try jumping the switch and get back.

Expert:  Kenton Guidry replied 7 years ago.
Sounds good. Please let me know.
Customer: replied 7 years ago.

I jumped the pressure switch- still get the error. Double checkes and the 24 V is there so the circuit is there back to the board. Checked the overlimit sensors- they check OK too.

 

 

Expert:  Kenton Guidry replied 7 years ago.
I believe you need to replace your control board because we have confirmed that the error still occurs when the switch is jumped.
Kenton Guidry and 2 other HVAC Specialists are ready to help you
Customer: replied 7 years ago.
I will order the board.
Expert:  Kenton Guidry replied 7 years ago.
Are you certain that there is nothing wired in series to the pressure switch?

If you are sure, then you will need to order the board.
Customer: replied 7 years ago.
I have ordered the board and will close or accept this thread after I install it (thurs or Fri) and see if this works. I was actually looking for more specific answers than to throw new parts at it. Not that your answer was bad, it was not. But I had already tested the switch and wiring for pressure and thermal overload circuits. They are good.
Customer: replied 7 years ago.
New board works. Thank you
Expert:  Kenton Guidry replied 7 years ago.
I am very happy to hear that. Thank you as well.

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