My a/c unit keeps blowing the 5 amp fuse
Hi, I have Done repairs on this problem many times. The problem is you will have to look around to find it and check some things I ask you to. This 5 amp fuse protects the 24 volt supply parts . You have high voltage coming into the unit and is stepped down to 24 volts for control parts like the thermostat, gas valve, safety switches and so on. The 1st thing I want you to do, so you don't blow to many fuses, you may blow a few more, but look on the circuit board where your thermostat wires are connected. You will see a Red R, a Yellow wire Y, a green wire G, and a White wire W. Draw you a picture so you don't forget, and take all of these low voltage wires off of the terminals. This takes the low voltage wiring and thermostat out of the circuit.They wont shock you either. Now, put in a new fuse and make sure the heater is plugged in.If the fuse does not blow you are real close to fixing the problem. This means the heater is OK but the wires going from there to your thermostat are touching metal by the heater. Look over the wires very well where they come in to see if they have been scraped on a sharp piece of metal. That's all it could be is one of these wires in the brown sheath is cut and touching metal.If the fuse blew again, then you have a problem with one of the other 24 volt componants shorted. The best way to check these componants is to unplug as many as you can. Just take the wires off and write down where they go. This is easier then you think. Take the wires off the gas valve. Off the other little switches and so on. Put a new fuse in and if it did not blow you no that one of the switches is the bad one. Take one at a time the wires you took off and plug them in. The one you plug in that blows the fuse is the bad part. Very easy but takes time.Write me back and let me know how you did. Hopefully, you found a thermostat wire that was touching metal. If every part that runs on 24 volts is not blowing the fuse, then the board you plug it into is bad. Make sure you have checked all limit switches, thermostat wires, gas valve and so on. Let me know what you find and we can go from there. I have done this so many times and the problem part or wire will be right in front of you. Just remember that when you unplug these things and the fuse does not blow, it has to be the one you plug in that blows it. Get back to me, I want to know. Good Luck and take your time, you can do this.
on Mar 19, 2013