A/C woes

I finally took my 87 xj in to have the a/c system vaccumed and recharged because I never had it done after I put in the missing parts and got tired of the intermitent cold to warm air. So after taking it in and being told that the system holds pressure like it should, having it vaccumed and recharged the dang thing still blows intermitently. Anyone have any ideas?

Does it quit blowing when you accelerate? If so, you have a vacuum leak.

It does, but only when I mash the pedal to the floor while towing my boat over the mountain. Otherwise no. The cold air fades in and out regardless.

More specifically you have a vacuum control hose / tube leak somewhere that controls the damper doors.

Find it, fix it (or them) and see if you still have any problems.