The repair involves removing the patch, cleaning any residue left and replacing the expansion valve in the A/C.
Customer may complain that A/C system has a hiss or whistle sound while the A/C is
operating. Customers may also notice a black patch hanging from under the dash
(mounted on the bottom of the evaporator) or even laying on the carpet. The hiss or
whistle sound is caused by the A/C expansion valve and the poor adhesion of the patch to