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Q: I am adding freon. I need to know the low side pressure if the ambient temp is 95 deg.

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I am adding freon. to my 2004 f150 5.4L. I need to know what the low side PSI should be if the ambient temp is 95 deg.
My car has an automatic transmission.

A: When the A/C compressor is running, the low...

When the A/C compressor is running, the low side pressure should be between 20-40 PSI. There is no spec for A/C pressure when the system is off though, rather they just specify a specific amount of refrigerant that should be in the system. This is done by using a refrigerant recycling machine, and recovering all the old refrigerant, putting the system under vacuum, and then putting in a specific amount. The same results can also be achieved by using a precise refrigerant scale and A/C gauges. I would not recommend using a simple can of refrigerant, as there is no way to accurately monitor the amount of refrigerant in the system. If you want to have this done for you, a technician from YourMechanic can come to your home or office to properly perform an AC recharge on your vehicle.

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