Mitsubishi Repair: 1.1 rpm to 0.75rpm when A/C is ON, servo kit, compressor check

Question
Hi, i just bought a 1996 lancer gli model (2nd hand) and on my first use, after travelling for almost 20mins (continous running) and then when i've stuck on traffic, the engine died  and it won't start again. Just for me to get-out of the location we replaced the battery by other unit. Then while the engine is running we put the original battery on it, and i'm able to use the car again on way back home (but without aircon). I noticed that my rpm is set to 1.1 (idle) and when i switch ON my A/C it drops down to 0.75, some mechanic says that it could be a SERVO kit problem, is this TRUE?? From my first used, i haven't use the car with the A/C switch ON for the worry of it could be in trouble again. The rpm is not fluctuating when A/C is switch-ON its just that is drops by 300-400 rpm. PLS> HELP

Answer
Nelson: To be honest I had no idea what an SERVO kit was so I looked it up on the interent. I don't think your car needs that. This mechanic that told you this, did he explain what it would do for your car and how much it would cost? I think the mechanic knows you don't know a lot about this car and is trying to make a bit of money off you. But again I sure could be wrong about the mechanic but just don't think your car needs a SERVO kit. Whatever it is. I would change that battery, check the cables as to the engine stopping while going down the road. I have had that happen over and over again on these little cars. They are nasty car on this bit, as they want their battery cables good and tight. So check that. Once you changed the battery for aother and then put the old one in. You must have got the cable tight enough to please the car. So I would check the battery, cables, make sure the cables are tight and clean. I would with the AC check the compressor. It sounds like to me, that maybe the compressor is bad. As you turn on the AC which kicks on this compressor but then pulls the car down, well the engine. As it takes more power to pull a bad compressor. Check also the belt that runs the compressor too. It could be bad also. I don't know where you live, but do you have an AutoZone place close? If so I would take your car in there and have it coded. That would rule out any problems with sensors or the car's computer. Your car is of the year of the cars that have a chance for a ill computer. I am not saying your car has this but it could. And this coding would rule anything like that out. I know what it is like to buy a used car and sometimes there will be problems with it. But with time you will work out the bugs and get it going like you want. A good tune up on the car would be good too. Stark plugs, wires, distributor cap and rotor. Change the air filter and oil. I have bought cars from people or dealerships that promied they changed the oil, air filter and did a tune up. Only they hadn't. So I would also try that. I do hope this helps you and good luck!