I know there have been multiple post on this issue but none really have answered my problem, I have a 81 240d manual transmission, and she has ran a lil hot since I got her, only boiled over once and that was last week after sitting in a drive threw with the ac on, now she has always ran hot while going down the freeway, usually between 90-100C but if I turn on the ac the temp gauge will quickly go above 100, I've replaced the thermostat, water pump and radiator, and I also flushed the block out and removed a lot of rust, nothing big though, so after replacing the radiator today I took it for a spin, she is running a lil cooler around 90 at 70-75mph but as soon as I turn on the ac the temp starts to rise till its just above 100C, I have checked with a inferred thermometer and the gauge is a lil off maybe around 10-15C to high, but the engine still hits 90-95C, what could cause this? Thanks in advance