Leak behind FRH wheel

just noticed a leak recently under the car, next to the front right hand wheel. i thought it could be the windscreen fluid at first, because of the position (i've got a LHD) but it seems as if it's water.

the other half said that something had dripped on her foot, as she sat in the passenger seat. when i stuck my head into the footwell to have a look, couldn't see anything obvious, but could hear a hissing sound i.e. air escaping through a hole?

i'm driving a Disco 1 V8, '91, LHD.

any help would be great!

p.s. did cross my mind that it could be something to do with the air con - but that has never really worked since i got the car. on another note - maybe someone could tell me why the aircon works on and off all the time?

hi
find the evaporator in the foot well of the passenger side look for the drin pipe take a piece of wore and stick it up there it will free the dirt and let the water from the a/c flow to the floor the drin pipe is located on the passanger ide of the car if lhd that is normal for water to come out a/c will work on and off one low on gas or thermostat located on the evaporator passanger foot well is faulty or blockage of dirt in expansion valve