Our programming team got to debug a problem where the compressor wasn't turning on. We tracked it down to a bad spike. The PWM cable was really loose fitting into the spike--we didn't have time to figure out what part of the spike was bad, but those cable connections don't seem very robust.
Here's how we debugged:
- verify software matches physical wiring
- verify compressor runs by hooking it to battery
- verify bus voltage at the spike
- verify pressure switch works by watching switch with multimeter while the system pressurizes (I didn't know if it was normally open or closed)
- verify the control signal to spike with signal analyzer (a multimeter would work--it's a PWM cable, but signal is simple on/off not RC PWM)
- replace the spike