Can't Get Compressor to Run

[slijin]

Originally Posted by ColonelThrtyTwo

There is no GND symbol on the Spike relay.

The B symbol on the Spike is logically equivalent to a GND symbol. The reason is that PWM cables usually have the ground cable color coded black.

Originally Posted by ColonelThrtyTwo

The switch seems to be closed normally (without pressure), so shorting them wouldn't do anything afaik.

The point of shorting the circuit across the pressure switch is to see if the pressure switch itself is broken. Alternatively, take a multimeter to the switch and check continuity (can also be done by reading resistance) and see whether the switch is tripped when you reach 115 psi (note that the switch opens when you reach 115 psi and will not close until the system falls below 95 psi).