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Posted by: helpful bob on 2010-02-08, 13:08:20

Sounds to me like you've a short or something draining power causing the comp to shut down part of it's circuit or go into a sort of safe mode , also the relays or grounds could cause such issues too. I'd look under the hood closely at all the charging system connections from the battery, starter, alternator, engine block grounds and especially the ground wires that ground things like the A/ C compressor circuit or any related electronic valves or sensors. To me it sure sounds like a bad ground wire or a rusted or corroded ground junction , also the comps in that vehicle use ground wires that feed certain sensors and it might run from the main comp to almost every sensors ground wire feed and to every comp.Just remember that if the comp sensor ground is bad this will cause faulty sensor and device readings or draw power that can shut down certain comp function controls thus causing less power etc. Here's an example of a possible trouble that you're vehicle could be having right now.The compressor or A/ C circuit is sharing a ground with the ignition module or the main comps ignition module ground.You're engine runs fine the ignition module is running within normal specs and isn't over heating internally but once you turn the A/ C on the weak or poor shared ground junction has the A/ C circuit drawing too much and that causes less current to be supplied to the ignition system , that could cause the coil or coils to over heat, poor spark to the plugs and thus poor or no acceleration.This could cause the coils to shut down or the comp to shut them down and also cause the coils to be internally weak or damaged etc. I'am just surprised that the engine light isn't on or at least some kind of error code is being stored in the comp system so check for any codes and due to the year of that jeep it is possible you might be able to pull the error codes yourself via the ignition and by counting the engine light error code flashes. I'd be checking all and any ignition spark devices especially for damages or cracking or bulges or discolouring, and especially the grounds and charging system connections , plus the wiring , also I'd clean these connections one by one with a wire brush , file , sandpaper etc to be sure that all connections are clean.Then I'd use a 12volt auto positive and negative led test probe to run some test probe tests to see if any wires have a weak ground or bad connection. Hope that helps and best of luck.By the way I'd be double checking to see if it's only happening with the A/ C on and making sure that it's not blower motor or fan relay or fan motor ground related bec it could be bec the engine gets hotter due to the A/ C on that the fan has to engage and any fan or fan relay shared grounds or 12 volt positive power junctions are weak etc. Some parts stores sell these probes for a bout 60 bucks but it's a great investment bec you can test not only the positive 12 volt wires or fuses or feeds but also the negative and ground strengths too.Just remember to check these circuits with no load and then with a load, also one of the relays could also have a bad ground or positive 12 volt feed. You might want to spend the cash and have the vehicle idling and then as it being driven tested via a auto scanner, diagnostic comp then try all and any vehicle functions or devices and see what the scanner finds as the engine and A/ C is running but be sure that they test it with a cool and warmed up fully engine etc. Remember that extreme heat or cold temperatures can cause wiring to act up especially if poor connections or internally corroded etc wiring, also relays etc can act up or comps etc.

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