I arrived at our clients home for a unit not cooling. Our client noticed the issue in the evening. I began upstairs and confirmed the indoor unit was running. I proceeded outside and found a burnt wire that had damaged the contactor from the capacitor. The capacitor was still testing in range. I further tested the unit because I was not getting proper voltage to the contactor. I found that the low voltage had shorted the thermostat and it was not sending the correct signal to power the outdoor unit. This most likely happened due to the contactor back feeding and damaging the thermostat. I showed all my finding to our client and he elected to replace the thermostat with a trane 824, replace the contactor and add a Hardstart kit to help the compressor. The outdoor coils were completely restricted with pet hair and debris. I did also preform a cooling maintenance today and washed the outdoor coil. Mr Bruno also provided a filter to be replaced today. We did discuss replacing air filte