# Trane XE 80 Control board fuse blows



## yuri (Nov 29, 2008)

Start over. Remove w at the board and then jumper r to w on the board. Sounds like you have a shorting w wire from the tstat. If you leave it on and jumper r to w it is still in the circuit.


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## ShotgunW (Dec 29, 2007)

Will do this in a moment. Thanks i will post what happens.


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## hvactech126 (Nov 11, 2010)

it sounds like bad stat or in stat wiring, short to ground on w


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## ShotgunW (Dec 29, 2007)

Removed W at board, Jumped r to w, as soon as it touched blew fuse, what next?


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## hvactech126 (Nov 11, 2010)

just to verify, you removed the white wire and then jumpered r to w and it still blew the fuse, if you have access to one, a 3 amp breaker will save you money on fuses. there is a control or safety circuit wire that is shorted to ground, this would be inside the furnace....


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## ShotgunW (Dec 29, 2007)

Don't have breaker so a short to ground inside furnace. Is this a visual find or what would be the steps to locating it?


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## hvactech126 (Nov 11, 2010)

pretty much gonna be a visual find.. when you checked the high limit, you did put it all the way back in the furnace with the screw, right? IF NOT THAT COULD BE CAUSE OF SHORT. Check for pinched wiring where doors hook on


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## ShotgunW (Dec 29, 2007)

Yes, high limit is mounted and screwed in. Could this still be a stat problem or did previous test eliminate that possibility?


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## hvactech126 (Nov 11, 2010)

yes last test proved stat not problem, but to make sure you can remove all the wires at the control board from the stat and jumper w to r and if it blow the fuse you know for sure with out a doubt its in the furnace


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## yuri (Nov 29, 2008)

Visually carefully look for any wires which could be touching the exhaust fan. If they did and melted that is a common short spot.


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## ShotgunW (Dec 29, 2007)

Unhooked all stat wires at control board, jumped R to W, blew fuse. Checked all wiring could not find any melted or other wise shorted wires. Any suggestions?


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## yuri (Nov 29, 2008)

Take the board off and look for burnt spot underneath it and on it.


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## ShotgunW (Dec 29, 2007)

No burn spots on back of board or anywhere.


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## hvactech126 (Nov 11, 2010)

from this point, call a pro, hard to suggest anything else without sitting in front of it, definitely a short though


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## ShotgunW (Dec 29, 2007)

Hey I understand, I have been repairing this furnace off and on for 10yrs now but this one has me stumped.
Thanks for all your help.


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## ShotgunW (Dec 29, 2007)

hey Guys, Can rollout switches , limit switches etc be tetsed without the furnace operating? Should I touch ohm meter to each side of the terminals and what readings should I get???


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## hvactech126 (Nov 11, 2010)

yes, set your meter to ohms, remove wires from switch and check for continuity between terminals, or for your case you check between terminal and ground


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## kaplaa (May 12, 2014)

*Trane XR80 Control board 5 amp blowing*

For me it was go outside. Remove cover where wires go into outside AC unit. Found bird nest and two wires which were bare from bird tugging on wires? Cut out old wire and used wire nuts to splice in new wire. Now COOL again :thumbup: Good luck ... 5 amp controls 24Vac ohmed out transformer and 24vac side was 2 ohms which is ok as I found out later looking at bare wires near bird nest


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## ben's plumbing (Oct 6, 2011)

Iam sure after 2yrs he has it fixed:thumbsup::thumbsup::thumbsup::thumbsuposted 2010


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