A/C Low Pressure Service Port in tight spot?

It has been a hot summer here, so my car A/C hasn't been working well. I need the front and rear A/C in my Navigator to be running for me to feel any cold. In the morning, when the sun has not been on for a while, I can get some cold. However, when I drive in the afternoon after the car has been sitting in the sun for a while, the car doesn't get cold even after I have been driving for a while with the front and rear A/C on.
So, I decided to extract whatever little refrigerant is left in the car and recharge it myself. The problem is the service port for the low-pressure side is horizontal and in a very tight area. I am using a four-way manifold set to extract. When I tried to attach the coupler at the end of the low-pressure hose, there wasn't enough space for me to attach the coupler to the service port even though the coupler is only 1.75 inches. Is there a way to find a coupler smaller than this?