There is an o-ring at the opening of each line behind the hose assy to the compresser.   One bolt in the center between the lines holds them to the compresser.  With the system empty, remove the bolt and pull out the o-rings, coat new o-rings with refrigerent oil, and reinstall them.   Then the system needs to be evacuated and recharged.    Don't leave the system open too long, or the dessicant will fill with moisture, and become ineffective.    However, the dessicant can be dried out by a LLOONNGG period of time on a vacuum pump.

You will also need a manifold gauge set along with the vacuum pump to refill the system.  If you want details on how to do this, let me know.

Be sure the system is empty before taking anything loose.  A rush of freon can cause serious hurt.  Legally, someone with a reclaimer must empty any remaining freon.

To evacuate the system, connect a manifold gauge set to the car and the vacuum pump.   The high side gauge and red hose connect to the high side of the car's a/c system.  This is the line from the compressor, to the condenser in front of the radiator, and on to the restriction.   Somewhere in this path is the connector.  From the restriction (orifice, valve) back to the compressor is the low side connection.   Connect the blue hose from the low side gauge to the connector found here.

The yellow hose from the center of the gauge set connects to the vacuum pump.    Start the pump and open both valves on the gauge set.   Run it for at least a 1/2 hour.  See that the low side gauge shows close to 30 inches of vacuum.   Then shut the manifold gauge set valves and shut off the pump.

Watch the low side gauge.  If it only loses a couple inches of vacuum and hold steady it's okay to charge.  If it bleeds off close to or at zero, there is a leak in the system.  If it drops part way, then stops and holds, there is moisture in the system.   Start the pump, open the valves, and give it more time.   If there is a lot of moisture, you could go up to 2 hours.  Repeat the test for leaks and moisture.

Once the system is holding good vacuum disconnect the yellow line from the vacuum pump.   Connect the freon supply.  Allow freon into the yellow line.   SLIGHTLY crack open the yellow line AT the manifold gauge set.  When you get a slight trace of refrigerent, close the line.  This bleeds the air out of the line that entered when you removed the vacuum pump.

Now start the car and turn on the a/c.  Open the low side manifold gauge valve.  Do NOT open the high side.   This will allow you to charge the system.   You should have the car on fast idle when charging.  Final pressures will depend on the ambient temperature.  If  you install the correct volume, you should be fine.

When done, shut the low side valve and disconnect the low side line, and install the service cap on the car.   This allows you to disconnect the line at it's lowest pressure.   Then shut off the car and allow the high side pressure to drop.  When stable ( less than a minute) disconnect the high side line, now also at it's lowest pressure.

If all else is good, you are now able to drive in cool comfort.

I have been at it awhile.  I now teach auto repair after fixing them for over 25 years.  I have written over 95 repair articles for trade magazines.  Had my own shop for 3 years, but I'm not a business man.  I hold 24 ASE certs.  All that and 60 cents gets me a coke.  I prefer the diet coke with splenda but an Iced Tea will do very nicely.

I have been at it awhile.  I now teach auto repair after fixing them for over 25 years.  I have written over 95 repair articles for trade magazines.  Had my own shop for 3 years, but I'm not a business man.  I hold 24 ASE certs.  All that and 60 cents gets me a coke.  I prefer the diet coke with splenda but an Iced Tea will do very nicely.

Glad it went well.

Payback?  Not necessary,......  Well maybe that Iced Tea.