The two 12 Volt lamps 'connection in series' gives you the 24 Volts and the #1156 gives a current limit of about 2.1 Amps (close to 2/3 of a 3 Amp fuse). Probably in this case (2) two old school #1156 automotive Back Up lamps Connection In Series. Its is called the Dim Bulb (or Dim Lamp) tester (some videos on YouTube). If I were there, and I was tasked to find your problem knowing the history you have posted here, this is what I would do. I am not a big fan of 'lil popper' type troubleshooting, except it may save fuses. I believe you swapped out the controller, so the 2nd controller should not be suspect, but 'like' electronics devices often have 'like' defects, keep this in mind, sad but true. Since your problem is happening when the blower is in operation, you should look at that low voltage circuit that operates the blower relay. Since my failed wire was the one that operated the condenser, the problem never happened in the winter. Eventually, within less than 1 minute, the uninsulated portion of the thermostat wire to the condenser touched together and a dead short on that control circuit blew the fuse. A weed-wacker had pealed the insulation off the wire and when the condenser fan moved the air thru the condensing unit, the wire fluttered in the breeze.
I traced the problem to the thermostat wire that went to the outdoor unit. I turned on the AC and after a 5 minute thermostat delay, the compressor contactor powered up for about a minute or less, then the fuse blew again. I replace the fuse and tested the furnace and everything was fine. I found that the fuse I added to the circuit failed (good thing I added that fuse). I replaced the transformer for a customer in September (cooling season was over and the heater would not work). Picture of the circuit board with the fuse and or the model number of the furnace might help.įor example: I had a similar situation with a bad transformer. Also, look at the fan circuit thru the circuit board. Look at the green wire from the thermostat to be in direct contact with the common somewhere. That fuse is to protect the transformer from letting the smoke out. the motor winding on the blower motor is line voltage (110v or 220v) and the fuse is on the low voltage circuit. Then use the following as a guide to select the correct fuse:3 Amp fuse for appliances up to 700 Watts,5 Amp fuse for appliances ranging from 700 to 1000 Watts,13 Amp fuse for appliances over 1000 Watts.Remember to never use a fuse which has a higher rating than necessary, as it can be dangerous.No. If you can’t tell what the rating is, or it’s not clear, you can check the rating of the appliance.Consult the appliance rating plate (often found on the rear or underside of the appliance) or look at the manufacturer’s instructions to find the wattage. Step Oneįirstly, check the fuse you’re replacing. An incorrect fuse however will continuously blow if under rated or fail to protect your equipment from possible catastrophic meltdown if it is too high. The reason for this is simply they are the most commonly available sizes and as such are cheaper to buy, whilst meeting the minimum protection required.
For example, a table lamp would have a 3A fuse where a washing machine a 13A but rarely will you find anything in between. Generally these days, most new, domestic appliances come with a pre-fitted moulded plug that already incorporates either a 3Amp or 13Amp rated fuse.