Q: Ac has no vacuum

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My o-rings went out on the a.c. lines going into the compressor. So i changed them and thought i pulled a good vacuum. So i charged it, but then as i was going down the road it started loosing the cool. So i got to autozone shut off the car. Popped the hood and i could hear and smell the freeon coming out of the lines on the compressor. I attempted to tighten the nut but it only leaked faster. So i went home and changed the o rings to a different set. And tried to pull a vacuum again but it would only get to negative 21 and hold there. Now it wont even get to negative 21 its at like negative 15 or 18.

My car has 204000 miles.
My car has an automatic transmission.

The o-ring size is very critical. Often, o-rings have to be procured from the dealer to ensure the right part. Components in the system can only be tightened using the OEM torque values. Under tightening and over tightening will create leaks. If the joint has been over tightened severely, it might be distorted and will not seal. The system needs to be thoroughly inspected for all leaks (typically using dry nitrogen, and an infrared refrigerant leak detector, with a small refrigerant charge at 200 psi) and repaired as needed. Note that vacuum on a system is only about 15 PSI or so. Really, to LEAK test a system, you have to pressurize it to operating pressure and that is in the hundreds of PSI. The best thing to do is request an air conditioning system inspection. The responding certified mechanic will come to your location, pinpoint ALL of the leaks and get this resolved for you. Once diagnosed, the mechanic will be in a position to give you a repair strategy to get the A/C system fully functioning and he or she will estimate the cost of the required repair. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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