I have a 2year old goodman straight ac, 3 amp fuse keeps blowing on the control board in my furnace since the first time I tried to put it in ac this season. Have tested all wires for shorts with tester, have traced to the C/U, not the low voltage wiring.

Remove the Y wire at the furnace. Jump y to G. See if AC comes on and fuse doesn't blow.

I have a 2year old goodman straight ac, 3 amp fuse keeps blowing on the control board in my furnace since the first time I tryed to put it in ac this season. Have tested all wires for shorts with tester, have traced to the C/U, not the low voltage wiring.

You say it is not the low voltage wiring. The fuse you are replacing is the low voltage protection, An over load on low voltage is what you need to look for.

Probably the contactor is shorted out.

Agree Josh. The contactor on outside unit(condenser) may be shorted. Try this. Unhook the low voltage wires from the contactor coil on the condenser. Now see if fuse blows when you turn it to cool. Let us know what you find, and we will try to help further.

Same problem here but following a thunderstorm. Tried jumping the Y to the G and it instantly fried the fuse. Would that indicate the contactor being shorted. Will try unhooking the low voltage wires tomorrow when its light out.

why did you jump y to g?
g to r for fan. Y to r for ac
w to r heat.
y to g = nothing.

did you jump this way at the stat? Or the control board??

Tried Y to G due to the post above, just tried Y to R but blew fuse as well. Fan works with AC and heat off. Turn either on and the 3 amp blows.

Do you have a heatpump or a gas furnace?

Heat pump

Have you run out of fuses yet? If not, try this: set the thermostat to cool with the temperature setpoint as high as possible. If the fuse blows, the reversing valve coil may be shorted. If not, lower the setpoint below the current room temperature. If the fuse now blows, the contactor coil may be shorted. As mentioned earlier, disconnecting the low voltage wires from the contactor will prove whether the problem is in the wiring. Be sure to disconnect the line voltage power supply from the outdoor unit before poking around in the control area.

Setting the temp above room temperature and turning the AC on did not blow the fuse. Lowering the temp till the AC tried to turn on did blow the fuse. Thanks for the tip, gives me something specific to test.

Pulled the outside low voltage wires to test for the contactor and the fuse didn't blow. Replaced the contactor and the AC now works like new. Total cost to fix $19.97.

Good job, now take that money you saved on a repairman and treat your family to that two-week Caribbean cruise they have been dreaming of... :p