Replacement Circuit Board for MaxxFan 4700K That Won't Shut Off or Close the Lid

Updated 10/11/2026 | Published 10/08/2026

Products Featured in This Question

Replacement Printed Circuit Board for MaxxAir Powered Lift RV Roof Vents w/ Exhaust Only Fan

(125)

$94.53

Replacement Printed Circuit Board for MaxxAir Powered Lift RV Roof Vents w/ Reversible Fan

(267)

$151.01

Question:

I have a Maxxair fan that will not shut off nor will the lid close except manually. I disconnected the power for now. It appears that the circuit board MA39FR is the replacement board but not sure. There is no label with a model number anywhere on this unit. I took the panel down and the circuit board has a number 4700K -U1.6 on it. It is a power lift fan, rain sensing, but is exhaust only. Please verify this is the correct circuit board before I order. Thank you

asked by: Walter A

Expert Reply:

Hey there Walter,

Based on the 4700K-U1.6 number on your circuit board, it looks like you have a MaxxFan 4700K. The correct replacement would be the Replacement Circuit Board # MA10A21275K rather than # MA39FR.

The fan running continuously and the lid not closing electronically are both signs of a potentially faulty circuit board. However, I'd recommend checking for damaged wiring, loose connections, or moisture/corrosion that could be causing a short before ordering a replacement.

What kind of RV is this on Watler?

expert reply by: Andrew N

Walter A.

10/8/2026

2018 Forest River Forester 3011DS

Andrew N.

10/8/2026

@WalterA Oh nice, those are top of the line. Let me know if you need any help with anything else Walter.

Walter A.

10/8/2026

It is on a 2018 Forest River Forester 3011DS. The board you said is for a fan that is reversible. Mine is exhaust only. So that does not seem like the correct replacement

Andrew N.

10/8/2026

@WalterA You are completely right that your fan is exhaust-only. MaxxAir actually uses # MA10A21275K as a universal replacement board for this series - it has the capability to reverse, but because your keypad doesn't have an "In/Out" button, it will safely operate strictly as an exhaust fan just like your original. The other exhaust-only board on this page is wired for a completely different sub-series and won't sync with your automatic lid lift motor. And the description lists your series (4700k) as a confirmed fit.

Pierre M.

10/9/2026

The circuit board i bought for my maxair fan worked perfectly, same wiring, it was an easy fix. Thank you etrailer.

Andrew N.

10/11/2026

@PierreM Thanks for the feedback Pierre!

Jjohn A.

10/10/2026

Hey Walter, I have the exact same fan as you and had similar problem with mine. When I took my fan apart, I discovered that the circuit board was corroded. I ordered the same part number you are looking at. Before I installed it, I coated the board with a spray on conformal coating. Installed it and everything is back in operation!