Your air conditioner could be blowing fuses due to some issues that begin and end in the fuse box itself. The purpose of the fuse or breaker is to protect the control board and the wiring in case of over amperage. Required fields are marked *. Time . – Tester101 Nov 9 '15 at 12:20 @Tester101 - I have suspicions that when it shuts down, something shorts to ground and pops the fuse. checked continuity on all wires from molex plug to ground only the green ground wire shows continuity. My 3 amp low voltage fuse pops when I … The line/low voltage is fine. 1 Posts . It’s important to note that changing temperatures can make these wires expand and contract, which could be affecting whether or not the electrical … 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. Problem: The fuse on my control board blows constantly. 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). Low voltage fuse blowing in furnace. If I remove the Honeywell TH8320V1008 thermostat from the wall, … It's been off for a month or two as we've been changing seasons here. However, in this case, the limitation would the 5 amp fuse on the circuit board. - Answered by a verified HVAC Technician That is to say did you accidentally downsize when you replaced it? Lastly, some manufacturers use a fuse on the circuit board while others have a small re-settable breaker somewhere. Members. Blowing Low Voltage Fuse Breaker Trip | Control Wiring Troubleshooting - I’ve got a 5 amp fuse that keeps popping on a circuit board. Transformer failure. By continuing to use this site you consent to the use of cookies on your device as described in our cookie policy unless you have disabled them. ... Start by disconnecting the red low voltage wire at the outdoor unit. A “blown fuse” can mean many different things–several of which have little to do with actual fuses. This video will show you how to isolate where the low voltage short is coming from. Mhu 80. That typically determines the limitations of the circuit. new posts. Check each pair of wires that come up to the base. I have a Trane XC80/XL19i system with a W/R 50v61-507 control board on the furnace. I bought a house 2 years ago with an AC system from 1992. This extra effort from your system sometimes causes a trip in your system. I found that the transformer in the air handler is blown along with the 3amp fuse. Replace the relay or contactor and problem solved. Helping You to Do It Yourself! Jump to Latest Follow ... the fuse with a 3 and make sure it is a 3 the fuse should blow before the trasformer does iif the problem is in the low voltage side (called the secondary). Previous 1 2 template Next. If you are getting 26.3 volts from the 24-volt transformer you are okay. Oct 2018. I have a Goodman heat pump and I keep blowing the 5amp fuse for the thermostat - Answered by a verified HVAC Technician We use cookies to give you the best possible experience on our website. Secondly, it is amperage. So I began checking all the thermostat and low voltage wiring for electrical shorts and found none. Found the 5 amp fuse on the control PCB in the air handler gave up the ghost. Is your air conditioner tripping the breaker and blowing a fuse? Any help would be appreciated. You will see that the fuse … Turn the thermostat to off and remove it from its base. This will determine wire size and transformer size. It is mandatory to procure user consent prior to running these cookies on your website. The condenser has nit been running so I cant see it being that. I don't see that its attacked to anything else in the house. Created Dec 22, 2010. I am still popping fuses and reading over 24 volts. Call Air Experts to Fix Your Air Conditioner Issues. I am still popping fuses and reading over 24 volts. I even installed a new t-stat. Ohming out the LV wires rarely finds the problem but again it does some times. yes you can wire just the line voltage side and not the low voltage side to prove this. An example of this would be a relay or contactor. 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. If the refrigerant level is low, your AC system has to work harder. I have a Goodman AC and gas heater unit and it keeps blowing. If the wire is fine with no dead shorts, then you look at the load. Changing the fuse is usually easy but resetting the breaker is even better since it does not require you to purchase fuses every time you blow one. Looked inside the condenser, and found nothing. Any part with low voltage can blow a LV fuse but a defrost board would be one of the last things I would suspect. Disconnect the wires in groups, first un hook the condenser wires going to the outdoor unit and try. 63.1k. All Time Today Last Week Last Month. Blowing Low Voltage Fuse Breaker Trip | Control Wiring Troubleshooting - I’ve got a 5 amp fuse that keeps popping on a circuit board. He tapped it up and left.. A few months later it happened again.. 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. Okay, I can give you some of the basics to help you but first, we need to clear a few things up. First I would check the incomming power. Read More. The voltage out of the transformer reads 26.3 volts. My 5 amp fuse keeps blowing. Filter. Amp draw is good too at the transformer. If the coil gets a dead short in it then there is your problem. This is typically done by adding up the VA or Volts-Amps ratings of all the loads in the circuit. I was told that this was the 5 amp fuses protects the low voltage side. Finally, it is likely you have a dead short from what you are describing but let’s go through the basics first: What is the purpose of the fuse or breaker in a control circuit? I had the same problem with mine.. Every troubleshooting tip I found said to disconnect the W (heat relay) and R (24V supply) terminals from the thermostat and jumper them on the control board. 3 Amp Control Board Fuse Keeps Blowing. Search. If you think that over-voltage is blowing the fuse (unlikely, but possible) you can always use a larger fuse. 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? We also use third-party cookies that help us analyze and understand how you use this website. We offer a full range of heating and cooling services including 24/7 emergency repair service. Second consider adding a fast acting fuse on the low voltage side that is smaller than the transformer current rating, that way you eat fuses instead of transformers while you troubleshoot. I replaced the fuse to see if it would blow open again but it didn't. Close. Or which wire has the dead short or bad load. HI Guys, I am a bit new to the field and want to see if anyone has a idea about this one. 3A Fuse on Circuit Board Keeps Blowing - Carrier Weathermaker 8000. Relays and contactors have coils in them that are energized through the wire. Your email address will not be published. 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. Yes, if you have a few extra fuses. Inspected the wiring coming out of the house to the condenser, and found it to be in good shape. 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