Spot John

John is a real trooper, coming early in the morning to avoid this awful heatwave we are in. Today will be the worse with temperatures at 100F/38C.  My little air conditioners really can't cope with it. Tomorrow will be a bit cooler, low 90's and then relief comes on Thursday.  On another, equally unpleasant note, I have a weird loud, high-pitched noise in the barn/garage that so far, no one can identify. My last hope is an electrician who I will call this morning.  Fortunately, I can't hear it in the house but what in the blazes is it?