Jake K. I arrived for a new customer no heat or cool call. I spoke with the homeowner and found that they turned the ac on and it stopped working and not the heat will not come on. I inspected the furnace first and found the low voltage fuse to have failed and the transformer to have been recently replaced. I installed my temporary fuse and inspected the system. I found that in heat mode the system comes on and runs normally. I then inspected the condenser and found the contactor to have failed causing a low voltage electrical short and was tripping the fuse. I made this aware to the homeowner and we decided to replace the contactor. Once the part was replaced I cycled the system on In heating and cooling modes and found it to be running correctly in both modes. There will be a one year warranty on the new contactor.