Arrived due to no AC call. Customer installed new thermostat. During installation wires may have touched to cause the 3 amp fuse on the board. Replaced fuse and fan began to operate but was not getting 24 volts to the outdoor system. Traced out low voltage circuit and 24 volt relay had failed. Replaced relay and system began to operate normal pressures 163/389 subcool 13 degrees. System is operating normal at this time. Thanks for your business