Troubleshooting A MaxxAir RV Roof Vent That's Opening Too Far And Closing On Its Own

Updated 11/03/2025 | Published 12/30/2024

Question:

I have a 2019 grand design 20rs fw i live in full time. Last year i replaced the motor for the unit and all was fine until recently. I have a 4951 series fan with rain sensor and wall mounted keypad to operate it. The cover is opening fine but when it gets to it maximum opening the cover starts to as best i can describe hiccup aa though the cover still has movement upward to finish when it appears from previous visual reference the cover has reached its maximum opening to shut off as it typically did?! I also noticed the cover closes on its own or did at least 1 or more times in the past and just last night with no rain or other outside moisture that i was able to feel outside when i stepped out to see if there was any light mist or sprinkler etc Thank you for your support and expertise! USA, Ret

asked by: Mike H

Expert Reply:

Hey Mike,

I wouldn't rule out some moisture in the air being enough to trip the sensor and close the vent overnight but if you're saying that the motor is still running after the lid is fully open then that could be an indication that the control board is faulty. Before replacing it you should check the voltage at the power wire for the unit. If you take down the inner shroud you should be able to see the wiring and can then test it with a multimeter. RV vents can act goofy if they aren't getting a full 12 volts to properly operate.

If you find the voltage is fine and end up needing to replace the circuit board you'll want part # MA10A04751KS for your 4951.

expert reply by: Kevin C

Robin H.

11/3/2025

Hey Mike, how did things go after you checked the voltage on your 4951 fan? Were you able to tell if the control board needed replacing or if the power issue was the cause? Your update could make it easier for others troubleshooting the same problem.

Mike H.

11/3/2025

The fan is working now or has since my original message but i did take my rig on a short trip since then but i have not tested the board either?! The fan or its plastic framework is making some noise now & it sounds like one of the plastic components where the fan blades rotate may be out of alignment or need to be adjusted so the blades stop catching on whatever piece it is rubbing against but otherwise knock on wood things are good & i have since pulled my spare original motor i had in storage & since temps in missouri will be mild this week i may test the board but i have to reattach my underpinning & prep to skirt & or heat my underbelly with either a diesel heater which i already have now to help prevent lines or tanks freezing & not have to get a loan to reppay for propane refills lol thank you for following up