my 94 3.4 about 121000 miles seems to be overheating when i put on the AC, like it will go over the middle and pretty muchwill keep going until i turn it off then it starts to cool the temp dow and stay down until i turn it on again. so what do u all think? coolant level is normal, oil is fine, can t be leaking in the heads cause i changed the gasket seals a few months ago, one of the freeze plugs is really rusting but a very tiny bit of coolent is dropping but very small. on top of that me and dad put this AC on and put refrigerant oil in the compressor but it allready had some, may question is should a certain amount be in the compressor or all the way to the top cause we filled it up to the top. i was thinking that maybe we put to much and some of the oil went into the system cause the car cools but not good enough, please need help on this!!!

 

Make sure the fan comes on when the AC is on. If the fan goes on and it still overheats with the AC on, you may want to change out the radiator as it tends tobe in the same conditionas the freeze out plugs. A marginal radiator may have problems handling the extra heat coming from the condenser in front of it.

 

ok what about the refrigerant oil how much should be in the compressor?

 

The lubricant, PAG synthetic lube, gets dispersed throughout the system. The total amount in the system including the compressor is 8 Oz. Typically 4 Oz sits in the compressor crankcase and the rest is gets dispersed throughout the system. Too much oil reduces the amount of refrigerant and the systembecomes less efficient. Minor leaks will only allow the refrigerant out, so normally only refrigerant needs to be added.

 

should he just take it in to make sure its right?

 

That would be a verygood idea.

 

ok thanks fellas i really needed that info my AC been like that for more then a year now. i did another test with the AC while driving today. first let me just say it is ridiculously hotdown here in miami like fires of HELL, so i really need my AC to work. i did put the AC at max with the level high as usually not cooling the inside (but thanks to u guys now i know cause i did fell the compressor to the top with the lub[8D]) the temp guage did go past the mid level but not to the point of complete over heat. the more i drove the level kept changing but by far not a complete over heat, i drove a good 34 miles today in the city and so far nothing to bad, opinions please...