I decided to dive into replacing the front evaporator, accumulator and condenser (since its not flushable). Everything in the system is new except for the front evaporator. The front evaporator wasnt as clean as I had originally thought. Last time I inspected it I removed the blower motor and used a mirror and I thought it looked decent. Bear with me because this story will bounce around a bit.
My evacuation machine process is that it recovers the refrigerant and when there is no pressure in the system it will pull a vacuum down to 10" and hold it for 2 minutes to check for off gassing. If off gassing occurs the gauges reflect that and it will continue to recover and once it hits 10" vacuum it will start the 2 minute timer over again. This process goes until 10" of vacuum is held with no off gassing for 2 minutes. My Excursion is the only vehicle I have ever seen that has off gassing (because its dual air system??) so it takes a while longer to evacuate the system completely. Even after the machine has said recovery is complete and the gauges show 10" vacuum, I can opt to recover again and it will usually recover 6 to 8 ounces on the first try and then maybe 1 ounce the next 1 or 2 tries. I dont believe its a fault in the machine because the gauges show a steady and holding vacuum, but once I start to recover again the gauges will usually go up to about 10 psi and slowly drop to 10" vacuum. I was discouraged because I thought something was wrong with my machine until this next experience.
So after recovery I jumped into removing parts to get the front evaporator out. I opened up the orifice tube joint and removed the orifice tube, removed the line from the top of the accumulator that goes to the compressor and then I had to go to my toolbox to get larger wrenches to open the connection that goes from the front evaporator outlet to the accumulator. As soon as I barely touched that connection with a wrench, hadnt even got the wrench into position, a blast of air comes out of the top of the accumulator where the connection is open for the line that goes to the compressor. It was a strong enough blast that it splattered pag oil on the bottom of my hood. The only thing that I can think of to cause this is there is a restriction of some kind in the evaporator that was holding pressure or something similar in the accumulator. I will cut the accumulator open and take pictures and also blow out the evaporator and take note of what comes out. Until then I am waiting on parts before I flush the entire system. I will try to attach pictures, hope this works.
This is the front evaporator. If I had known it was this dirty I would have replaced it a long time ago. But this issue isnt causing my low side pressures to be high correct? Hoping its a flaw in one of the components and all will be well after the rebuild.
This is a sketch of how the Excursion system is set up. Another picture is attached lower that you can see the connection that requires larger wrenches.
I took this picture right after the air and oil blasted out of the accumulator port that is open.