Lot of older fords use a line connector I need help with to remove. I have a leak at one and need to repair. They're round with no threads, the part store said they needed a special tool to release them, I have one but need instruction on using it, also is there a seal or o-ring to replace once its apart and does it just press back together or do I use the tool again? Thanks.

If those are the old spring-lock type, simply select the appropriate sized tool to slip into the coupling and release the spring to remove the line. The system is under pressure so it must be discharged before removing ANY lines.
To reassemble, lube the o-ring with refridgerant oil, align the connection and simply slide the two back together until it clicks. Try gently pulling the two apart to make certain the connection is secure.

Remove the A/C tube lock coupling clips and, by using the proper line separator tool, separate the spring lock couplers. One coupler (5/8-inch) connects the accumulator to the compressor and the other coupler (3/4-inch) connects the accumulator to the evaporator.

It helps to inject PAG oil on the old spring, which may be somewhat corroded. This allows the spring to easily release (expand) and allow separation with the tool. Yes, just coat the new O-ring with PAG oil and press the ends together--you will feel it lock.

Big help thank you