I replaced the evaporator coil in an AC unit.
I was called to a home to check on a unit that was not cooling. I found that the unit was low on refrigerant. I added more refrigerant to the unit and it is now cooling properly.
The customer called in to report that their heating system was not working. I arrived at the house and found that the heat was not working. I checked the thermostat and found that the heat was not coming on. I checked the furnace and found that the heat exchanger was cracked. I gave the customer an estimate for the repair and they agreed to have the repair done.