PR,
Don't know what your problem is but I have an '89 Mustang (which is basically the same as yours); it lost all of its R-12 charge because of a bad leak in the suction line (hose running from the outlet of the accumulator to the inlet of the compressor.)

I decided to convert my Stang to R-134a and I just wanted to let you know that the fox body Mustang is a good candidate for the retro if done properly. That means a good flush, new accumulator, new o-tube, fresh oil and a good long vacuum. You also have to readjust the cycle switch to cut-out at about 19 psig....

But first you need to determine what's wrong with your A/C system. It might be something as simple as a blown fuse or broken wire.
Good luck,
Phil

Follow Ups:

• Re: 1991 mustang a/c prob ashley 11/12/2002 (0)