Found fuse blown in air handler. Discovered rub out in thermostat wire in the condensing unit. Confirmed with customer to repair it and replace fuse. Ran system in heat mode and found suction pressure low with system defrosting every five minutes. Heating TXV sensing bulb not responding to temperature change. Gave quote for replacement and put in a part quote form to check whether or not the unit has a Part warranty. Tried to run systems heat strips and found thermostat want sending signal. Had old used thermostat in my truck that I installed for the cost of labor with no warranty to get the customer by. Unit is heating but will not do so effectively until TXV is replaced.