A/C Low Pressure Compressor?

Thank you for your reply. Yes, that is the service port that I have been trying to attach the coupler to. I attach the video below showing the service port without coupler (first 2s) and with the coupler (last 2s) at the end of the blue hose. The problem is that the space beyond the service port is so small that I am unable to line up the quick coupler well and clip it onto the service port. My question is that where can I find a coupler that is small enough to fix it to the service port. Is there a different type of coupler to attach the hose to the service port?

This is it. Thanks.

For some reason, the connectors that I bought do not fit because of the small space. I thought the quick connect I am using which is only 1.75 inches long is too long. There is one object on the other side of the service port that is not letting the quick connect fit horizontally so I can then push it onto the service port.

Sorry for the long break in my replies. Fall, winter and spring came, making it less urgent to have A/C. I finally found a quick connect that worked. I measured the pressure and it was 0 psig on the low pressure and high pressure sides. I was able to pull a vacuum of -29 mm Hg on the system, and this held for about 1 hour. I then connected 1 can of Supertech R134A refrigerant to it and tried to draw it into the low side service port. I could see some liquid going in through the sight glass, the pressures on both side increased with the low side going up and then decreasing, and the high side going up slowly. After a short while, the liquid flow stopped. Even though I kept going for a while, it seemed the refrigerant wasn't going in anymore. I was only able to get about half the can content in. I then started with a fresh can, a similar thing happened with only half the can going in. I tried a third can can and only about half or one-third went in. From the three cans, I have only been able to get a maximum of 18 ozs used out of the 36 ozs in the three cans. The capacity of ny A/C is 62 ozs. The final pressure was 45 psig on the low side and 110 psig on the high side.
In trying to find out what is going on, I found online that the A/C compressor might not be engaging.
1) How do I know if the compressor is engaging?
2) Where is the compressor on my navigator so I can get a visual confirmation?
3) What can I do to make sure the compressor engages
4) How do I make sure that all the contents of a can is used and used quickly?
Thank you in advance for your help,
Moyo.

Sorry, I forgot to add this to the questions above.
5) Is it advisable to drive the Navigator a few miles around? Maybe that will distribute the refrigerant around the system and make recharging a bit easier?

I followed the articles you posted above on A/C not working. I measured the static pressure and the pressures were zero. I then decided to pull a vacuum again on the system. It did go down to -30 psig but it wouldn't hold vacuum for 45 minutes no matter how much I tried. I therefore decided to take it to the mechanic. They did a diagnostic on the AC and found out that the compressor is bad. They recommend that I change the compressor, the front and rear evaporators, front and rear condensers etc, Now I am in the process of deciding whether it's worth spending that amount on this old car. Thanks.

Thank you very much. I will start a new thread.

I found out that my A/C was not cooling. I then measured the pressure but it was 0 psig both on the low pressure side and the high pressure side. I evacuated the system but the vacuum would not hold for up to 1 hr. I then took it to a shop for diagnostics. I also note that the SUV has an additional A/C in the rear. The result came back that the compressor was bad and the shop has proposed for me to replace the compressor, the front and rear evaporators and condensers and driers.
Is it possible for me to just replace the compressor or at least reduce the scope of the work? Thanks in advance.