mobilehomerepair.com

colemanm#g8c10020mud11a. The 3amp fuse on control board blows on call for heat.I unhooked t-stat wires at furance and jumped r-w same prob.Wiring is ok unhooked and read all low voltage wires.Would bad board cause fuse to blow.Thanks in advance for any help.Electricman

Hi,

Get a new wire and connect between t-stat W and board W and see what happens.



Thanks,
Robert

robert, I tried the new wire nothing happened untill i hooked to r
and w then blew the fuse. Thanks for your reply any other ideals,I have tried everything i can think of. I unhooked all low voltage wires and tested them they showed ok ,do u think it could be the board. Thanks again, Electricman

Hi,

With what has been checked, the board having a short is likely.

Have you removed it and looked at back for any burn spots ?


When you unhooked wires from furnace and jumpered R and W, was that at the board or at a terminal board for furnace ?



Thanks,
Robert

Robert . i jumpered the r_w at the furance and the fuse blows , if i turn power on with t-stat unhooked ,sometimes both fans run but not all the time.after checking i found out they had changed boards but the furance run after that Then i was told the furance was running but through the nite the heat quit and he shut power off and back on then the fuse blew.sorry but i just found out this information,i havent charged a dime for my time so i may tell them to get a more exp tech although i think it has to be board or a control going to ground,I dont expect you to keep helping me but i do thank you very much for all you have done,THANKS AGAIN Electricman

Hey,

You're very welcome, happy to help. Can you send me a copy of the wiring diagram ?

With W wire at board disconnected and unit powered up with call for heat, IF all is fine.

Then when you connect the W wire to board and power back up and fuse blows, most likely a shorted circuit in the board.

Check and be sure that there is not high voltage coming in. Test across the W wire and C on board for 24vac.



Thanks,
Robert

Robert. Ithink i found the problem or it healed itself. the last roll out switch was bad going to ground i jumped it out and furance run installed new switch seems to be ok. THANKS FOR ALLYOUR HELP AND Iwill try not to bug you guys so much Thanks again electricman

Hi,

That's great, hope it keeps running good . You're very welcome, happy to help.


In a case like that, that is why I asked for wiring diagram.


Get you an inline ATC Automotive fuse holder and a lot of 3 amp fuses.


When this happens, splice it in at transformer power wire on 24vac side.

Then, looking at wiring diagram, reconnect one section of circuit at a time.

Keep following the diagram and adding a section at a time until fuse blows.


Then, if that wire is ok, the component it connected to is bad.



Take care and best wishes,
Robert