Converting our powered roof vent

[Tommy_II]

I haven't begun yet, but the PCB for the roof vent failed and a replacement is $189. I'm thinking I can make some mods that won't require the PCB. a double pole, double throw momentary reversing toggle switch for the vent lid motor and a PWM (pulse width modulation) controller for the fan. The two switches are less than $30. Pulling in new leads is the one thing I may have and issue with. If the current lead from the control panel to the fan was stapled when they installed it that will be a problem. Am I overlooking something that makes this undoable? The fan has a brush motor so the PWM controler will work.

 

[John From Detroit]

If you have the skills yes. Might not even need the PWM controller if the fan is low/high or low/med/high all you need is likely a multi-position switch) ..

I've done stuff like that.

However if you have a rain sensor.. you lose that function.
Also make sure the motor controller can start the motor.. way more than run current.

 

[workinonit]

If the current lead from the control panel to the fan was stapled when they installed it that will be a problem.

Staple wire?? It's a miracle they pulled it. They don't own staples or tie wraps.

 

[Mark_K5LXP]

I modified my speed control (tapped nichrome wire) with a new series ceramic resistor and selector switch such that it now has a high and a low range. The new PWM based ones probably already have this range but "low" on mine wasn't very low and I wanted something whisper quiet. My fan now has six speeds but I rarely use any more than 2, so a PWM control might be superfluous. This did the trick, I can leave it run all night and it is just enough to draw air through the open bedroom windows. Current is pretty low too, I recall under an amp. Point being is you can easily do this, I don't think the PCB has any control over the motor than on/off (or is that the lid switch?), which you can accomplish with the speed or temp control. The lid could be actuated manually with the manual knob.

Mark B.
Albuquerque, NM

 

[Tommy_II]

Staple wire?? It's a miracle they pulled it. They don't own staples or tie wraps.

You're right, no staples. It's about 6' from the fan to the control panel. There was enough cable to run the length of the 36' trailer.

 

[workinonit]

Yea, they used up the savings they had on staples and tie wraps pulling excessive amounts of wire.

 

[Wasillaguy]

I modified my speed control (tapped nichrome wire) with a new series ceramic resistor and selector switch such that it now has a high and a low range.

I have contemplated doing this. Agree that low speed is not low enough.

 

[John From Detroit]

Speaking of a Tapped Nichrome wire..

I once had a car where the heater speed control was nothing more than a wire wound resistor with a slider (Like a volume control or Variable Potentiometer.. Man was that a long time ago.

 

[Tommy_II]

Got my stuff yesterday. Just need some 14/4 cable. I let you know how it goes.