O.K., being how this is an aftermarket add on, and no PDC relay for the A/C, then this is left up to you to find just where the aftermarket A/C relay is installed. If you can find it, then remove it and see if the issue persists. Best of luck as we are all flying blind on this aftermarket install. Of course you can always dissect the controls and see if there is any wire rubbing going on. But on a stock YJ, the A/C and Heat are separate with respect to your current issue except the defrost. If all avenues have been exhausted, then perhaps we can visit testing the load side of the blown fuse to ground while wiggle testing harnesses and switching controls in order to find the cause.