I arrived at our clients home for the main unit not cooling properly. Our client said it was working fine but when they returned home it was not coming on outside. I proceeded outside and began testing the equipment. I found evidence that rodents had compromised the low voltage wires for the outdoor unit. I did some further testing and found the outdoor control board to be compromised. It was not sending the correct power to the contactor. I contacted Trane and they informed me the system is no longer under warranty. The board is in stock and we will pick it up tomorrow and return to complete the full repair. Our client elected to have me bypass the board as a temporary fix today and turn on the air conditioning only. I also covered some of the compromised spot of the wire inside the heat pump. The unit is cooling on departure.