I have a 2008 Lexus RX 350 and the A/C has not been blowing very cold. I bought a can of 134 freon. Is it okay to install or could I do damage to the engine? Also, where is the charge nozzle on this engine?

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the low side charge port has a black port on it and it's the only one that the add valve on your can will fit. NOW you are guessing by adding as you have no idea how low it is. IF you want to try, do a little at a time. But the only real way is to hook up pressure gauges high and low and measure the pressure until it's correct. If you overfill it that can lead to serious consequences. It takes a guy like me 1 minute to analyze it in person with gauges hooked up to low and high side.