They hiss when they're getting low on gas (uncondensed refrigerant expanding
in the expansion valve). At some point the loss will mean the low pressure
switch will drop out, then you'll get nothing.

Your guess is probably correct. Most likely to be the condensor, or
corrosion on the pipes under the pipe clamps. You might find some obvious
corrosion, otherwise you need the proper equipment.

www.poolecool.co.uk

The air just failed. One day it was not cold but can still hear the hissing
under the glove compartment. Th enext day no hissing, I guess it leaked all
the freon. In your opinion what is the most common item that fails.
Tx