Troubleshooting laser counter fan behavior

In my PA-II I’ve noticed one of the laser counter fans doesn’t spin when power is connected while the other fan spins constantly. Is one non-spinning fan a de-facto indication of a failed laser counter or could it be a failure of the motherboard or even normal behavior? Unpowered the fans can both be spun manually with equal ease so I feel certain it is neither a bad bearing nor an obstructed blade. Would it be feasible to temporarily swap counter channels to better isolate the source of the problem (if it’s a problem)?

In other words, are the laser counter fans always running? Do they ever stop, and restart, during normal operation?

I’ve always seen them both running. You can check the readings the two channels to see if one is radically different from the other.

The fans in the laser counter should always be running. It is possible that an object passed through the laser counter in your device and damaged the fan in the process. We can take a look if you email us at contact@purpleair.com with your device ID.

UPDATE: The issue of the stopped fan turned out to be an inadequate power supply that was providing 0.12 amps at 4.7 volts. A different but successful supply unit provides 0.10 amps at 5.1 volts. Both supplies are high quality and rated at 5 volts @ 2.0 amps. I wouldn’t have thought a fan would be so sensitive to voltage.