Alright here I go, The car is a 91 nissan 300zx na 2+2. the problem i am having is that my car starts to over heat after about ten minutes of having the air conditioner on. but if i turn it off and i am not in stop and go traffic the car will still stay warm, not hot. it will stay inside the lines about 3/4 of the way up. but if i leave my ac on the gauge will continue to clime but after i reach 3/5 of the way i shut it off and turn on the heater to relieve some of the heat and roll with the windows down. but if i accelorate to rmps above 3.5k it will drop rapidly evan if it is in netral. I have replaced the water pump, timing belt all of the cooling hoses, the radiator, thermostat, alternator, all the drive belts, front oil seals, oil pump gasket, transmission fluid and filter, head gasket, valve cover oil seals, upper and lower plenum seal, fuel injectors and connectors, vacuum lines, upgraded air filter, spark plugs, and ac compressor oring. and that car is still not running right. there is no coolant leaks, I checked it with a Snap-on coiling system tester and held pressure at 15 psi for over night. i cleaned the condenser and removed all blockage. also the only part of the cooling system i have not replaced was the belt driven fan which i will soon replace. so any advice will help alot except some one telling me to get a new car lol. thanks!