For a better experience, please enable JavaScript in your browser before proceeding. I bought a house 2 years ago with an AC system from 1992. I called an HVAC guy and he charged me $75 opened up the outside unit and there was a wire rubbing on the unit.. Without the proper amount of refrigerant, your AC has to work harder to maintain its performance. A forum community dedicated to Do it yourself-ers and home improvement enthusiasts. Blowing Low Voltage Fuse Breaker Trip | Control Wiring Troubleshooting - I’ve got a 5 amp fuse that keeps popping on a circuit board. Finally, the re-settable breakers are especially good for troubleshooting problems such that you are describing. the low voltage wires are clear of shorts, so I don't know what to do next and it's 15 - Answered by a verified HVAC Technician I have a Goodman AC and gas heater unit and it keeps blowing the 3 amp fuse on the circuit board after running for a couple of hours. Once I select emergency heat the 5amp low voltage fuse blows. I’ve seen many things cause fuses to blow and breakers to trip. 383. Call Air Experts to Fix Your Air Conditioner Issues. 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. If you disconnect the wires on the furnace and the fuse still blows, the problem is in the board. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. This will determine wire size and transformer size. Make sure you have a good fuse and then reattach them one at a time. Collapse. Your email address will not be published. Also, drop in voltage will cause an increase in amperage, so see if you have 109v coming in to the transformer, or if the transformer is breaking down, and when at peak use is tripping the fuse. Mhu 80. Hello, So I went out on a service call for this 5 ton carrier unit the other day and found a blown 5 amp fuse. If you disconnect the wires to terminals Y and C, and the fuse stays good then you are using a heat pump (based on your location of MN). Replace the relay or contactor and problem solved. Disconnect the wires in groups, first un hook the condenser wires going to the outdoor unit and try. Search. This makes it hard to answer the question, “Why do fuses blow?” You might be wondering, then, how to tell if a fuse is blown–an actual fuse, that is. This category only includes cookies that ensures basic functionalities and security features of the website. Low voltage fuse blowing in furnace. This is typically done by adding up the VA or Volts-Amps ratings of all the loads in the circuit. JavaScript is disabled. Reduced airflow can lead to blown fuses in a heat pump system. VerticalScope Inc., 111 Peter, Suite 901, Toronto, Ontario, M5V 2H1, Canada. Problem: The fuse on my control board blows constantly. Coronavirus Update: We care about your health and continue to service our customers safely. So I began checking all the thermostat and low voltage wiring for electrical shorts and found none. We offer a full range of heating and cooling services including 24/7 emergency repair service. Online. On the advice of a buddy who had a similar issue, he told me to check the capacitor on the outdoor unit. Undersized duct work and blowers or incorrect control applications can cause the blower not to operate properly. If your air conditioner is tripping the breaker or blowing a fuse, there could be a few issues at hand. Looked inside the condenser, and found nothing. Page of 2. Posted by 3 years ago. Answer: We have many customers ask how to find a low voltage short when the low voltage transformer is burning up or the fuse on the control board constantly blows? If you think that over-voltage is blowing the fuse (unlikely, but possible) you can always use a larger fuse. There are a number of reasons why your air conditioning system keeps blowing a fuse. Wiring in any control circuit is rated for a certain amount of amperage based on temperature. These cookies will be stored in your browser only with your consent. A “blown fuse” can mean many different things–several of which have little to do with actual fuses. Lastly, some manufacturers use a fuse on the circuit board while others have a small re-settable breaker somewhere. I replaced the transformer but the 3 amp fuse blows every time I change the thermostat to heat. It helps to know at just what point in the system operation the fuse pops. We'll assume you're ok with this, but you can opt-out if you wish. AC keeps blowing 3A fuse. My 5 amp fuse keeps blowing. You start by checking the obvious, shorted wires or connections, then check for shorted coils, safetys and everything else that goes into and out of the board. I even installed a new t-stat. HI Guys, I am a bit new to the field and want to see if anyone has a idea about this one. If the refrigerant level is low, your AC system has to work harder. You will see that the fuse … Turn the thermostat to off and remove it from its base. I have a Tempstar Model NTC6100KFG1 gas furnace. If it still blows the fuse disconnect the thermostat wires then put them back on 1 by 1 starting with the red wire. These links will lead to you purchase a product from another company. Using wire sizing tables from the NEC or UL we can find the proper wiring size for the application given the design of the circuit. checked all wiring found no damaged wires disconnected gas valve and heat assisted limit control still blows fuse. Well, the fuse blew. Or which wire has the dead short or bad load. Faulty Transformer. I had the same problem with mine.. When designing the control circuit the designer needs to figure out how many loads are on the circuit. yes you can wire just the line voltage side and not the low voltage side to prove this. I bought a house 2 years ago with an AC system from 1992. This time i was ready, again a wire bare rubbing on the outside unit. The 3 amp fuse in furnaces are usually on the low voltage side of the transformer, so I wouldn't think motors would have anything to do with the problem. If your air conditioning system is blowing fuses or causing your home’s electrical system to short out, contact the team at Air Experts Heating & Cooling. Heating, Ventilation, & Air Conditioning. 3 Amp Control Board Fuse Keeps Blowing. Any help would be appreciated. Furthermore, when the fuse blows you will know which wire is causing the problem. ... Start by disconnecting the red low voltage wire at the outdoor unit. Good luck, sometimes finding why a control voltage fuse is blowing can practically send you to the looney bin. The condenser has nit been running so I cant see it being that. 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. blue_can. Out the door I ended up paying $51 for the contactor relay and DCB another $36 for the solenoid coil (all replaced by me) then $49 for the service call and $100 for the Low Voltage Wiring Repair. I've removed low voltage wires coming from thermostat and ac unit and I've removed the 9 pin connector for the 24 volt circuit within the furnace. After resetting the circuit breaker and replacing the fuse, if the fuse keeps blowing, there might be an electrical short in the electrical system that supplies the electricity to the furnace. Designing the control board blows constantly cookies on your browsing experience the voltage out the. Point in the circuit me to check the capacitor on the R terminal pair wires... You have any other ideas amps is more than sufficient another company helps us pay for the website to properly... Us pay for the website line voltage side the transformer but the 3 amp fuse in that. Lastly, plus or minus 10 % is the generally accepted tolerance for electrical! A LV fuse but a defrost board would be one of the fuse ( unlikely, but you always! Check the capacitor on the R terminal blowing a fuse, there is some wiggle room,. Reviews, accessories, classifieds, and more short is coming from shorted. Some manufacturers use a larger fuse to see if anyone has a idea about this one experience! Builds, styles, scales, reviews, accessories, classifieds, and found none navigate... Come join the discussion about tools, projects, builds, styles scales. Figure out how many loads are on the circuit accepted tolerance for most electrical components including transformers realize. 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