Furnace Control Board Blowing Fuses

Your furnace s control board has a separate fuse that protects it from getting too hot.

Furnace control board blowing fuses.

If you haven t been diligent about maintaining your furnace all its parts will have been silently and steadily collecting debris and dust. But for those who ve recently encountered one common issue a furnace blowing its fuse before scheduling that tune up it may be due to one or more of the following reasons. If someone is poking around your furnace and is not too careful they could more wires so that they come into contact with the furnace s wire frame causing them to short and blow the fuse on the furnace board. Loose electrical cables there could be loose electrical cables inside the circuit box or somewhere in your ac which could be causing a short circuit.

If the fuse blows when you have no low voltage wires hooked to the furnace then you have an internal problem like a bad limit gas valve connection or control board. This will blow the fuse on the control board causing the draft inducer to not start which then stops the rest of the furnace functions from working properly. Furthermore i would remove all the control wires from the board. Assuming this is a fuse on the low voltage side coming off the 24 volt transformer it s possible the contactor in your condensing unit has shorted out causing it to blow the fuse.

We have a really good tool that you can use to save fuses when troubleshooting low voltage shorts called the lil popper. Pay close attention to where the thermostat wires where the wires go through the body of the furnace or air conditioning unit. Electric furnace thermostat control wire. The 5a fuse that is blowing is a control fuse for the 24v control side of the system.

The most probable of these are 1. Make sure you have a good fuse and then reattach them one at a time. Fuse on the circuit board blowing in your case you likely have a dead short somewhere in the wiring or a bad load that is going short to ground causing the fuse to blow. Many times the thermostat wires will short out against the body of the furnace or air conditioner.

There could be several reasons why air conditioner keeps blowing fuse in circuit board.