Compressor won't turn off - PCM?

[Jon Stratis]

Originally Posted by rich2202

Try a new PCM. If there is no switch, then the it should not turn on.

I'll echo this. Also, contact CTRE about it - this is a bad/dangerous failure mode for the PCM, and they may want to investigate why it's acting this way.

[Hadi379]

Check the power wires to the compressor and pressure sensor where they connect to the pcm, we had a similar issue caused by exposed wire contacting at the pcm

[GeeTwo]

I agree - check for swarf (metal shavings) or another source of a short across the pressure switch terminals. If you can't find anything, replace the PCM, preferably working with the vendor or CTRE.

[ratdude747]

Another thing to check: make sure the pressure switch isn't shorted out; with the compressor running, unplug the switch. If the compressor keeps running, it's a PCM issue (or swarf intrusion as some have mentioned). If not, the switch or its wiring is shorting out.

[Minerbotics4827]

We have unplugged and replugged everything in three times, checking for shorts every time. We didn't find any metal shavings, and even took the PCM apart trying to find any. Even if we unplug the pressure switch while the compressor is running, the compressor stays on. We are ordering a new PCM to test tonight. Until then, we have the pressure switch plugged in as a digital input and are controlling the compressor through code in teleop while we test.

[GeeTwo]

Originally Posted by Minerbotics4827

Until then, we have the pressure switch plugged in as a digital input and are controlling the compressor through code in teleop while we test.

Don't forget that for competition you need to either switch back to a PCM or put the compressor on a spike (R88 C and D).

[ratdude747]

Originally Posted by Minerbotics4827

We have unplugged and replugged everything in three times, checking for shorts every time. We didn't find any metal shavings, and even took the PCM apart trying to find any. Even if we unplug the pressure switch while the compressor is running, the compressor stays on. We are ordering a new PCM to test tonight. Until then, we have the pressure switch plugged in as a digital input and are controlling the compressor through code in teleop while we test.

Yeah, I'd RMA that PCM. That's clearly a PCM issue.