Listening to refrigeration and air conditioning units

I was walking through Oxford with Charlotte Heffernan listening to the sounds of the street. We started at the top of the Westgate car park and eventually found our way down to one of the small high sided lanes that characterises Oxford City Centre. As it opened out into George Street Mews we became aware of a chord and traced it to a refrigeration unit mounted on a wall behind a mesh fence. The sound mingled with several air conditioning units close by. This was recorded using a Roland R-26 with the internal mics.