Troubleshooting A MaxxAir Fan That Shuts Down When A USB Charging Port Is Being Used

Updated 07/12/2023 | Published 07/11/2023

Question:

When I plug my phone into the usb port and the maxxair fan us running at low speed the fan shuts down. Doesnt seem to matter if Im plugged into shore power or using the house battery. 2022 Thor Chateau 22e

asked by: CJ

Expert Reply:

MaxxAir vents like the # MA00-04000K run off of 12 volt DC power and with the symptoms that you're having I suspect that the USB charging outlet is running off of 12v DC as well and is tied into the same line as the vent. When you draw power for the charger it's taking it away from the vent, causing it to shut down. A lot of manufacturers will tie smaller appliances together to make the installation easier so it's very likely that this is the case for your motorhome.

Normally the vent should pull the same amount of power and just blow the fuse but I've seen a lot of weird behavior from vents in enclosed trailers where they tie them into the lights for power. To solve this you could trace the wiring of the vent and then disconnect it from the line with the charger and run it directly to your DC distribution panel so that it isn't competing for power.

expert reply by: Kevin C