Probably the top 2 suspects:

1. Due to normal wear on the compressor clutch, the gap has increased. When the system runs for awhile and the clutch and its electrical coil heat up, there is no longer enough magnetic power to hold the clutch engaged. You can run it at road RPM (2500-3000) for awhile at rest with the hood open and watch the clutch. You can also use a feeler gauge between the clutch plates and see if exceeds spec.

2. If the air flow in the system is restricted (always run with all vents open and a clean cabin filter) or the evaporator thermostat is out of spec, the system can overcool and cause the water that condenses in the evaporator to freeze and block airflow. With the decreased airflow, cooling is reduced.

3. Check youtube for videos. As always, there is a lot of BS out there, but if you sift through it you will probably find some decent info.

 

Quick follow up. Took back to mechanic and he tested power to relays. He then put MDX on the lift to test power to the compressor and found a loose connector. It has now been a week with no problems!

 

My 2008 MDX developed a slow steering fluid leak about 3 years ago. I had it repaired by replacing the Return Hose from the base of the steering assembly to the aluminum elbow of the Return Line. This did not cure the problem. Last week I discovered that the Aluminum Elbow was perforated. I replaced it and that solved the problem. This was more of a seepage that occurred in warm weather only but did require fluid top ups.. I bring it up because perforated aluminum tubing is the last thing one would suspect in a line with plastic hoses.