Problem: My 24-volt low voltage transformer continues to burn up. This is the second transformer. What could be the problem?
Answer: I have encountered this problem several times. Most of the time the problem ends up blowing the fuse on the control board, (if your control board has a fuse) instead of the transformer. In most cases, the thermostat wires have shorted out somewhere and the thermostat wires are the problem. I have seen other components inside the air conditioning system with coils and electronics cause the transformer to burn up. I have seen shorted reversing valve coils and contactor coils cause this problem several times. Most of the time it is in the thermostat wiring. This can be a pain trying to find out where the short is located because it can be so very time-consuming. In order to find the problem I would turn off all the power, take all the low voltage thermostat wires loose from the thermostat, air handler, and outdoor unit. I would take a digital meter set to ohms and check between all the wires with the meter. You should not get a reading between any two wires if the wires are in good shape. If the wires are good you would need to test the components from each wire or terminal to the ground. The meter should not move. This is a pain sometimes finding the problem. Many times I would find the thermostat wires shorted where the wires were installed going through the furnace body. The vibration of the furnace or air handler over time had torn through the wire insulation and caused a short. Sometimes animals will chew through the wires and cause a short. Sometimes sunlight on the wires over time will rot the insulation and short out the wires. If you need a transformer we sell transformers on the following page: Please click here if you are interested in seeing the low voltage transformers we sell. If the fuse on your control board continues to blow and you are tired of replacing fuses then we have a Lil Popper fuse reset tool that we sell on the following page: Please click here if you are interested is seeing the LiL Popper fuse reset tool. If your furnace or air conditioner does not have a fuse to protect your low voltage circuits then we have a fuse installation kit on the following page: Please click here if you would like to see our fuse installation kit. I hope you can easily find and fix the problem. Below we have two really good information YouTube Videos made by grayfurnaceman and Word of Advice TV titled “How to replace a transformer without burning up the new one” and How to Find a Short in an HVAC System. Many thanks to grayfurnaceman and Word of Advice TV for making these great informative videos. If you have any questions please email us anytime. Our email address is: firstname.lastname@example.org or comment below.