How do replace my AC unit with a Maxxair fan?

[daboognish88]

I got rid of the rotten old AC unit and want to replace it with a Maxxair. Problem is I don't know how to wire it.
Do I have to run all new wire to the battery (or wherever it runs to) or can I use the same wire but convert it somehow to connect to the Maxxair? I suspect it will be hard to run new wire through this ceiling.
The existing wire from the AC says its
12/2 WG, 600 V, (UL), ETTCOFLEX, TYPE NM

I think the AC only ever ran on shore power. So I'm not sure if this will even connect to the RV marine battery.
Any tips?
Thanks.

[daboognish88]

2112 wrote:
You're making this too hard on yourself. Plus you do not know the load demand of any 12VDC branch you tie into. You could be setting yourself up for blowing fuses.

The air conditioner black wire is connected to a breaker on the A/C side of your power distribution panel. The breaker should be identified as AC on the panel label. The white wire and bare ground wire are connected to the common and ground bars.

Assure camper is unplugged from power and battery is disconnected. Disconnect the three wires identified above and pull out from the back side of your distribution panel. With masking tape and permanent marker, fold the bare wire back and secure with tape. On the tape identify this end as "moved from air conditioner to DC MaxFlo fan". Move the wires to the DC side of the panel. Now you need to select a fuse if an empty one is not available. I suggest the furnace. You most likely will not run the furnace and this new fan at the same time. Connect the white wire to the furnace connection. Connect the black wire to the large lug identified as "BATT -".

On the fan side fold the bare wire back, wrap with masking tape and write "From AC Wiring". Connect the fan red wire to existing white wire and the fan black wire to the existing black wire and install the fan.

Put it all back together, connect to shore power and/or battery. Your new fan should work. Just remember you might blow the fuse if you run the fan and furnace blower at the same time. Have a spare fuse on hand.

I appreciate the detailed instruction but my motorhome features two separate electrical systems that are far apart from eachother and I think your instruction only applies if it weren't so separated. One system is a 12 volt system operating off the battery and the other is a 110 volt system operating on outside electrical hook-up. Its this outside shore power system that would have fed the AC with power. Seeing as I will only be operating the fan on the battery system I've realized it doesn't make sense to use the wire running to the 110 volt system. Unless I'm missing something here (which I could very well be).

[seaeagle2]

I don't want to hurt anyone's feelings but based on the questions asked, this might be a project best left to a pro.

[2112]

You're making this too hard on yourself. Plus you do not know the load demand of any 12VDC branch you tie into. You could be setting yourself up for blowing fuses.

The air conditioner black wire is connected to a breaker on the A/C side of your power distribution panel. The breaker should be identified as AC on the panel label. The white wire and bare ground wire are connected to the common and ground bars.

Assure camper is unplugged from power and battery is disconnected. Disconnect the three wires identified above and pull out from the back side of your distribution panel. With masking tape and permanent marker, fold the bare wire back and secure with tape. On the tape identify this end as "moved from air conditioner to DC MaxFlo fan". Move the wires to the DC side of the panel. Now you need to select a fuse if an empty one is not available. I suggest the furnace. You most likely will not run the furnace and this new fan at the same time. Connect the white wire to the furnace connection. Connect the black wire to the large lug identified as "BATT -".

On the fan side fold the bare wire back, wrap with masking tape and write "From AC Wiring". Connect the fan red wire to existing white wire and the fan black wire to the existing black wire and install the fan.

Put it all back together, connect to shore power and/or battery. Your new fan should work. Just remember you might blow the fuse if you run the fan and furnace blower at the same time. Have a spare fuse on hand.

[Cummins12V98]

SoundGuy wrote:

As I said, if it were me I'd just pull +/- 12 vdc from a nearby overhead light and be done with it ... now that's "simple". 😉

daboognish88 wrote:
Yea I decided I'm just going to leave the original AC wire alone in case I or someone else ever wants to reinstall AC.
I've tried going from a nearby light but the wire must be damaged somewhere along the line.

SoundGuy wrote:
That makes no sense - if the light works there has to be +/- 12 vdc at the light so just tap off that source.

drsteve wrote:
It's probably a switched circuit...

So turn the switch on and control the light itself with it's own switch, if doesn't have a switch then replace it with one that does.

When I tapped the light wire it was for a light that was a switchable one and the wire had power all the time.

[SoundGuy]

As I said, if it were me I'd just pull +/- 12 vdc from a nearby overhead light and be done with it ... now that's "simple". 😉

daboognish88 wrote:
Yea I decided I'm just going to leave the original AC wire alone in case I or someone else ever wants to reinstall AC.
I've tried going from a nearby light but the wire must be damaged somewhere along the line.

SoundGuy wrote:
That makes no sense - if the light works there has to be +/- 12 vdc at the light so just tap off that source.

drsteve wrote:
It's probably a switched circuit...

So turn the switch on and control the light itself with it's own switch, if doesn't have a switch then replace it with one that does.

[qtla9111]

daboognish88 wrote:
I got rid of the rotten old AC unit and want to replace it with a Maxxair. Problem is I don't know how to wire it.
Do I have to run all new wire to the battery (or wherever it runs to) or can I use the same wire but convert it somehow to connect to the Maxxair? I suspect it will be hard to run new wire through this ceiling.
The existing wire from the AC says its
12/2 WG, 600 V, (UL), ETTCOFLEX, TYPE NM

I think the AC only ever ran on shore power. So I'm not sure if this will even connect to the RV marine battery.
Any tips?
Thanks.

Thanks for posting this. I have wanted to get rid of that worthless boat anchor that sits on my rv roof.

It noisy, way oversized for my small TT so you're constantly frozen out, and it creates that obnoxious humming-vibrating feeling inside the rig.

I was thinking of just having a dome but the fan sounds much better.

[drsteve]

SoundGuy wrote:

As I said, if it were me I'd just pull +/- 12 vdc from a nearby overhead light and be done with it ... now that's "simple". 😉

daboognish88 wrote:
Yea I decided I'm just going to leave the original AC wire alone in case I or someone else ever wants to reinstall AC.
I've tried going from a nearby light but the wire must be damaged somewhere along the line.

That makes no sense - if the light works there has to be +/- 12 vdc at the light so just tap off that source.

It's probably a switched circuit...

[SoundGuy]

As I said, if it were me I'd just pull +/- 12 vdc from a nearby overhead light and be done with it ... now that's "simple". 😉

daboognish88 wrote:
Yea I decided I'm just going to leave the original AC wire alone in case I or someone else ever wants to reinstall AC.
I've tried going from a nearby light but the wire must be damaged somewhere along the line.

That makes no sense - if the light works there has to be +/- 12 vdc at the light so just tap off that source.

[drsteve]

daboognish88 wrote:

As I said, if it were me I'd just pull +/- 12 vdc from a nearby overhead light and be done with it ... now that's "simple". 😉

Yea I decided I'm just going to leave the original AC wire alone in case I or someone else ever wants to reinstall AC.
I've tried going from a nearby light but the wire must be damaged somewhere along the line. So I tried to go from an further small wall mounted fan wire but that didn't work either. So yea a lot of these wires seem to be dead. So I guess I have to run new wires after all. I don't know how I'm going to do that because they make it impossible to run new wire. I'm guessing everything was wired up before they put on all of the inside panels and such. :R

Yes, that is exactly how they wire it up. Given that there is no easy access to 12v, I would go with SidecarFlip's idea and just use the existing wire. Label it all clearly, and call it good.

[daboognish88]

As I said, if it were me I'd just pull +/- 12 vdc from a nearby overhead light and be done with it ... now that's "simple". 😉

Yea I decided I'm just going to leave the original AC wire alone in case I or someone else ever wants to reinstall AC.
I've tried going from a nearby light but the wire must be damaged somewhere along the line. So I tried to go from an further small wall mounted fan wire but that didn't work either. So yea a lot of these wires seem to be dead. So I guess I have to run new wires after all. I don't know how I'm going to do that because they make it impossible to run new wire. I'm guessing everything was wired up before they put on all of the inside panels and such. :R

[SoundGuy]

SidecarFlip wrote:
The wire is already there, just use it for the intended purpose, intent is 12 volts this time. I think you guys are over complicating an easy task.

How is labeling each wire at each end for what it is and thereby avoiding any confusion later "over complicating an easy task" when it's simply common sense. :h As I said, if it were me I'd just pull +/- 12 vdc from a nearby overhead light and be done with it ... now that's "simple". 😉

[drsteve]

SidecarFlip wrote:
Why wouldn't the 120V solid copper wire that supplied the defunct ac unit work for powering the Maxair fan? The wire don't know if it's 12 volts dc in it or 120 volts ac.

I'd trace the wire back to the power source, disconnect it and reconnect it to a 12 volt source to power the fan, Simple and issue solved. Use the existing wire.

Good thinking. Since there's nothing else on that 120v circuit, you can do what you want with that wire.

[Cummins12V98]

There should be a light near the AC, simply route a wire from there to the Fan.

[SidecarFlip]

SoundGuy wrote:

christopherglenn wrote:
And make sure you flag the wires as 12 volt only - so the next guy doesn't set something on fire by putting them back into the 120 volt breaker.

Ac wiring black is hot, white is neutral (ground). DC wiring black is ground red is hot (+12). In this case I would use the white as a +12.

And therein lies the rub ... Romex used to feed 120 vac would normally be colour coded black & white with a separate ground wire, black being hot and white being neutral. If converting use of this cable for feeding 12 vdc I'd do just the opposite you're suggesting and use black for + 12 volts and white for - 12 volts. To avoid any confusion later on the solution is to label each wire at both ends. All that said, I personally wouldn't convert a 120 vac cable for 12 vdc use and would instead just pull +/- 12 vdc from a nearby overhead light.

Pulling wire in a home and in an RV are two entirely different animals. The wire is already there, just use it for the intended purpose, intent is 12 volts this time. I think you guys are over complicating an easy task. Done that kind of thing before myself. While I would prefer stranded over solid for low voltage application, the draw of a vent fan and voltage drop won't be an issue at all.

[SoundGuy]

christopherglenn wrote:
And make sure you flag the wires as 12 volt only - so the next guy doesn't set something on fire by putting them back into the 120 volt breaker.

Ac wiring black is hot, white is neutral (ground). DC wiring black is ground red is hot (+12). In this case I would use the white as a +12.

And therein lies the rub ... Romex used to feed 120 vac would normally be colour coded black & white with a separate ground wire, black being hot and white being neutral. If converting use of this cable for feeding 12 vdc I'd do just the opposite you're suggesting and use black for + 12 volts and white for - 12 volts. To avoid any confusion later on the solution is to label each wire at both ends. All that said, I personally wouldn't convert a 120 vac cable for 12 vdc use and would instead just pull +/- 12 vdc from a nearby overhead light.