[fan44644]

I have been blowing the 3 amp fuse when my ac is turned on. It runs fine with the heat on. The fault code is for a short in the 24v wiring. I checked my ac unit outside and couldnt find and shorts. I also installed a new thermostat this winter so i double checked the wires going into it and they all seem to be correct. Thanks in advance for your help it has been 88 degrees the last 2 days here in cincinnati and getting a little toasty...:furious:

 

[yuri]

Disconnect the 2 AC wires from outside where it attaches to the circuit board in the furnace and turn the AC on. If it does not blow then the outdoor wiring REALLY is shorted. Very common to get chewed by dogs/rodents and hit with weed whackers or dried up and insulation bare from the sun and UV rays.

 

[fan44644]

i am trying that now thanks!

 

[fan44644]

ok i took off the red and black (cool and spare)from the circuit board and the fuse blew. next i took off the heat and spare blue and yellow and it blew again.

 

[yuri]

Those are the fan 110 volt wires. Remove from Y and C the low voltage wires to the outdoor unit.

 

[fan44644]

ok thanks ill try that I really appreciate your help

 

[yuri]

make sure you leave the thermostat Y wire on the board when trying it. Y is the call for cooling.

 

[Marty S.]

Also double check that you don't have G and C confused on the thermostat.

 

[fan44644]

Ok guys I removed the blue com wires and left the yellow y wire attached and it didn't kick out. So now I just have to find the shorton the outside blue wire right?

 

[yuri]

Either wire going outside could be shorted. You just removed part of the circuit , C common but it proves that there is a short downstream from the furnace. It could be shorted inside the outdoor unit in the electrical box or possibly the contactor is sticking and drawing too much current. 95% chance is the damaged wire scenario.

 

[fan44644]

if the contactor s bad would the fuse blow instantly? I triple checked the ac unit and the thermostat and can not find a short i also replaced all the terminals

 

[yuri]

If it blows instantly then there is a short. I have never had a contactor draw too much current and have done this for many many yrs but I have heard it is possible. Thermostat wires can be shorted along ductwork, have staples pulled thru them so you may have to run a new wire to find out or call a Pro. Should have #18 gauge wire and not any thinner stuff like telephone wire.

 

[fan44644]

ok yesterday when i was supposed to take off the blue com wire to check for a short i took off all 3 blue wires. realizing my mistake today i started with the blue wire that ran to the ac unit and it was fine it ended up being a problem with the thermostat so i have about 2 feet of slack that i have pulled thru the wall and havent found any broken wires. im ready to pull out my hair