Installed an aftermarket a/c and ran all summer. Idled at 800-900 RPM's when ac engaged. 1000-1100 disengaged. Suddenly the idle is now at 1600-1650 rpms, with ac engaged, and 1300-1350 rpm disengaged. No check engine light. Common problem or do I have a PITA on my hands. The computer below the brake booster has been rehabbed by PO as the case was opened and there has silicone added to the internals. Anyone have any thoughts?