Trane XE 80 control board


  #1  
Old 12-04-10, 09:20 AM
S
Member
Thread Starter
Join Date: Dec 2007
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Trane XE 80 control board

My trane XE 80 blows fuse on the control board when the call for heat comes. AC works fine. High limit switch tests fine. What would be the next step to diagnosing the problem???
 
  #2  
Old 12-04-10, 09:51 AM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 4,469
Upvotes: 0
Received 1 Upvote on 1 Post
Usually the cause of low voltage fuses blowing is that the thermostat wire has been cut on sheet metal duct work and is shorting out to the duct work/ground.

So check that first. That this happens when the thermostat calls for heat makes it more likely.

One of the thermostat wires is energized with 24 VAC all the time. The other is energized only when the thermostat calls for heat. So that's probably the one that is shorted to ground.
 
  #3  
Old 12-04-10, 10:03 AM
S
Member
Thread Starter
Join Date: Dec 2007
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks, I will start checking stat wires now. Done with wires.
I unhooked all stat wires at control board and jumped r to w and fuse blew. I check everywhere inside furnace for exposed wires etc, did not find any. Any suggestions?
 

Last edited by ShotgunW; 12-04-10 at 10:46 AM.
  #4  
Old 12-04-10, 10:59 AM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 4,469
Upvotes: 0
Received 1 Upvote on 1 Post
Well, it's not the thermostat wires by your description of the problem. Another perfectly good theory shot to heck by reality!


It's gotta be something downstream from the W connection.

I'd check the circuit board for any metal impinging on it or anything hanging from it.

What amperage fuse are you using?

Also, the low voltage circuit goes around to the flame rollout switches, limit switch, pressure switch and such. Check all that for a bare or disconnected wire or something impinging on an electrical contact.
 
  #5  
Old 12-04-10, 11:59 AM
S
Member
Thread Starter
Join Date: Dec 2007
Location: USA
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Can the rollout switches etc be tested with an ohm meter by touching each of the contacts and what should the readings be??? Using 3 amp fuses
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: