Upon arrival system was not on and thermostat was blank Went into attic to inspect system and noticed light switched was flipped down Followed electrical line to source and it was the switch for high voltage to the furnace Asked homeowner if he flipped switch himself and he said it must have been the exterminator that was there recently Flipped switch up and waited for thermostat delay to insure system was operating System came on in cool Went back into attic to make sure system was cooling effectively System had a temperature Delta of 18 and still continuing to drop System was left on cool upon departure