Compressor not Receiving Voltage (Need quick help if possible, currently at regional)

[Golden_Tiger]

Hello, we are currently having some issues with our compressor, as it is not receiving any voltage to it to turn on when we enable. We checked connections to it, the PCM is receiving voltage as it lights up green. The compressor worked fine two weeks ago at our last regional, but we are not entirely sure what the issue is. We are trying to get a new PCM to see if that is the issue, but we would like to receive any suggestions if there are any.

Thanks, this practice day has been a bit more stressful than desired.

[nighterfighter]

If you stick a multimeter into the PCM compressor ports, do you see any voltage?

Is your pressure switch hooked up correctly?

[Golden_Tiger]

We do not see any voltage at all when using the multimeter, and the pressure switch is hooked up correctly. That's why we believe it may the PCM.

Anything helps though.

[nighterfighter]

Is the switch working? Try taking it out of the PCM, and stick 2 wires into the PCM pressure switch port. See if you get voltage coming out, and then short the 2 wires together, and see what the voltage is.


But it does sound like you have a dead PCM, if everything is plugged in correctly.




You do have it plugged into the CAN? And the Vin is plugged in correctly?

If you could post a picture, that might help people troubleshoot.

[Jon Stratis]

Try shorting the pressure switch inputs, then see if you get any voltage on the compressor outputs while the robot is enabled. Best way to do this is to unplug both the compressor and switch, then use a short wire to bridge the two inputs for the switch.

Also check on the driver station that the PCM version number shows up - if that isn't there, then there's something wrong with the CAN bus or the switch.

If the version number is there and shorting it doesn't work, then there's probably something wrong with the PCM.

[Arthur3103]

You need to prove that parts of the system are good. Start at either the PDB or start at the compressor. Test one component at a time and be methodical.

Check the wiring from the PDB to the PCM. Take out the wires and reinsert them in the PDB and PCM.

Take out the compressor wires and reinsert them.

Remove the PDB fuse and push it back in again. Perhaps change the PDB fuse to a spare.

Will the compressor run when given 12v from another source - do not connect to a tank if trying this. You want the compressed air exhausting to the atmosphere for safety.

If the compressor is good, test the pressure switch.

Good luck.

[nighterfighter]

I'd also make sure that you have the PCM 12V input plugged into the PDP, not the VRM.

[Sperkowsky]

Use the online tool. Click the self test button and see what it returns.

Also, you are at a regional surrounded by people that can help you much quicker. Find a csa ask a team everyone will help.

[cbale2000]

Our team had an issue with our compressor earlier in the year, though I think it ended up actually being an issue with the code. Not sure of the specifics but might be something to look into.

[ctt956]

Make sure it's programmed properly. Maybe try disconnecting all tanks/hoses from the compressor and enabling. If it runs by itself like that, it's probably something like a pressure switch or PCM.

[Golden_Tiger]

I apologize for our long delay, we found that the pressure switch was the problem, and we are trying to fix it now.

Thanks to all for the suggestions. They are greatly appreciated.

[Golden_Tiger]

We have found that our pressure switch is staying open regardless of pressure. We have a Nason SM-2B-115R/443, which is meant to stay closed normally, but open at 115 psi, and close again if the pressure drops below 95 psi. We do not know how to fix it at all, so if there is any suggestions that would fix this too that would be great.

[Mr V]

Originally Posted by Golden_Tiger

We have found that our pressure switch is staying open regardless of pressure. We have a Nason SM-2B-115R/443, which is meant to stay closed normally, but open at 115 psi, and close again if the pressure drops below 95 psi. We do not know how to fix it at all, so if there is any suggestions that would fix this too that would be great.

Go to spare parts and get another one, that is why they are there.

[rich2202]

Originally Posted by Golden_Tiger

We have found that our pressure switch is staying open regardless of pressure. We have a Nason SM-2B-115R/443, which is meant to stay closed normally, but open at 115 psi, and close again if the pressure drops below 95 psi. We do not know how to fix it at all, so if there is any suggestions that would fix this too that would be great.

No user serviceable parts. Only solution is to replace.

[ctt956]

Originally Posted by rich2202

No user serviceable parts. Only solution is to replace.

"No user serviceable parts"?! Well, we'll just see about that! That's never stopped me from disassembling and/or repairing something! *insert evil laugh here*

Note: if you do attempt to disassemble the pressure switch, don't try to use it again.