How do replace my AC unit with a Maxxair fan?

daboognish88 wrote:
I'm sure this is incredibly naive (which is why I'm gathering as much info as I can before doing anything) but what I'm really confused about is how I would connect the positive and negative 16 gauge wires of the fan to the one 16 gauge wire that would normally be running the light or furnace.

There isn't just one wire running anything, you need two - one for positive, another for negative. If this basic electricity fact escapes you then it's a pretty good indication you ought to leave this to someone who does understand electrical wiring. ;)

I'm sure this is incredibly naive (which is why I'm gathering as much info as I can before doing anything) but what I'm really confused about is how I would connect the positive and negative 16 gauge wires of the fan to the one 16 gauge wire that would normally be running the light or furnace.

Correction: my motorhome USED to have a furnace but no longer does. I thought it was run off 110 volt shore power but it actually runs off the house battery. I just noticed too that there is no wire running the lights from the 12 volt fuse box. Its missing.. at least at that spot.. and there is no fuse and one of the prongs for the fuse holder is broken. I thought I recalled at least one of the lights working at one point when I got the van which leads me to wonder if the previous owner just wired the lights to the furnace fuse when original light fuse holder broke. I'll have to investigate. But seeing as how the light fuse prongs are damaged I should probably get a new fuse box first anyway.

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.

The light doesn't work. I originally thought it might have been a blown bulb but alas. So unless there's another way I think I'm going to have to run a new wire.

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).

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.

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.

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.

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.

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.