[beerobber]

Success! Thanks for the tips. I don't know when we would have ever thought to create separation between the radio and the PCM, but that did it.

Our PCM was less than 1 inch from the radio. Our first validation was to slide a triple-thickness sheet of aluminum foil between those components, and that was enough to allow the compressor start immediately and run until the pressure switch cut it off. Solenoids are also reliable. The PCM is signaling green and happy.

After a quick debate about the appropriateness of aluminum foil as a crucial component in a competition robot, we moved the radio (only 2 wires) and used zip ties to give it a new home about 9 inches from the PCM.

Some said the aluminum foil gave the robot a NASA-like quality, but others pointed out that blanketing components with a highly-conductive material that blocked air flow was probably not going to help get us to Einstein. So it came off before the robot went back in the bag.