“Prepped” For a 2nd AC

[Kemoy]

As the summer temps reach higher and higher, I’ve decided to bite the bullet and add a second air conditioner. My 2020 Flagstaff 26FKBS came prewired and “prepped” for a second unit. However, no one seems to know the answers to the questions I’ve asked, and I refuse to believe that what I’m hearing from these so called professionals, are my only options. I feel like I’ve read every forum thread on the internet trying to figure it out. There’s not really a manual for adding a second AC and it’s frustrating. Too many options and not enough guidance in what to choose and how to go about it.

My end goal is to have a Mach 15 unit in my bedroom, that can be controlled by the dual zone Rv Comfort ZC thermostat that controls the front Mach 3.

What sounded like a simple transition when I first purchased my camper, has turned into a serious head ache. Any advice from anyone who’s successfully added a unit would be appreciated.

[latner]

Is there an existing roof vent in the bedroom? If there is, it most likely is the spot for a second ac. The roof opening would have been framed for the ac and the wiring run to that point. The vent and ac both use a 14" x 14" opening.

[Kemoy]

Correct! I have the 14” vent, and the wires that come down after you take the white sheath off, the yellow power supply, and 6 colored wires- red, blue, purple, black, white and white with a black strip.
I have a sticker above my light switch in the bedroom that says Ac Prep sensor location, and my thermostat is dual zoned, and the 13.5 k Mach 3 is ducted in the front.

I was told at the dealership when I purchased my RV that it would all sync together. Now I keep being told that I will have to be satisfied with the controls on the face of the vent on the ceiling, and that it would have to be separate in all the ways. Not ducted, no thermostat control, and no use for the sensor location sticker.

[KSH]

Any update? Looking to add a second ac as.well.

[Kemoy]

Update! I went with my gut, and after doing an obnoxious amount of research with very little information found, I purchased the Mach 15, and then I got the zone control box, the ceiling assembly for a ducted unit, and the room temperature sensor!

The installation instructions that come with the ceiling assembly were my guide on how to do most all of it, especially how to connect the wires that came provided with the “prepped” trailer. While the back room wasn’t actually “ducted” all that I had to do was cut the Styrofoam where the ducts would have been and that tied into the duct system. I fished the room sensor wires out from behind the light switch and spliced the sensor in.
Put it all together, and it worked like a charm.
The Thermostat controls it like it should, it’s ducted in, and it looks and runs exactly like it should.


I can officially say that I did it, and with next to no help from the so called professionals that I called for advice.

[Csbadvisor]

Originally Posted by Kemoy

Update! I went with my gut, and after doing an obnoxious amount of research with very little information found, I purchased the Mach 15, and then I got the zone control box, the ceiling assembly for a ducted unit, and the room temperature sensor!

The installation instructions that come with the ceiling assembly were my guide on how to do most all of it, especially how to connect the wires that came provided with the “prepped” trailer. While the back room wasn’t actually “ducted” all that I had to do was cut the Styrofoam where the ducts would have been and that tied into the duct system. I fished the room sensor wires out from behind the light switch and spliced the sensor in.
Put it all together, and it worked like a charm.
The Thermostat controls it like it should, it’s ducted in, and it looks and runs exactly like it should.


I can officially say that I did it, and with next to no help from the so called professionals that I called for advice.

Good job,always satisfying to successfully complete a project. I’m confused when you say it was not ducted. I have a 2020 FKBS prepped as you mentioned. I do have ducted vents in the bedroom that does bring air from the front AC. Are you saying the 2nd unit would not run from those ducts, just the vents on the AC unit? Again congrats on your project.

[Kemoy]

[QUOTE=Csbadvisor;2355513]Good job,always satisfying to successfully complete a project. I’m confused when you say it was not ducted. I have a 2020 FKBS prepped as you mentioned. I do have ducted vents in the bedroom that does bring air from the front AC. Are you saying the 2nd unit would not run from those ducts, just the vents on the AC unit? Again congrats on your project.[/QUOTE



Thanks! It was a large feat for little me.
Sorry for the confusion though, my second ac site was not pre-ducted with the main unit. There was about an inch of Styrofoam between the hole for the ac and the vents on either side. When I called the dealership, and Forest River, both places told me that there was no option to have my second ac tied into the duct system. So I mention this to identify that although I bought a ducted ceiling assembly, I had to go in and cut away the styrofoam to allow the air access.

I’ve almost decided that there is no rhyme or reason to my camper. It’s been through a lot of shop time trying to fix some of the things that they either missed, or didn’t install properly the first time. So maybe they just forgot to cut my foam before they shipped it out!

[allandra42]

We did this today we added another air conditioner and we can’t figure out the air conditioning thermostat wiring it asks for different color wires than we have and what is the temperature sensor in the wall.

[pirlbeck]

Originally Posted by allandra42

We did this today we added another air conditioner and we can’t figure out the air conditioning thermostat wiring it asks for different color wires than we have and what is the temperature sensor in the wall.

I am dealing with the same problem of the colors not matching the installation instructions and I started a post above about this problem this morning. I ended up dropping the grill off of the existing air unit and drawing a diagram of how they were connected as the factory used the same color of wires at both units.

The temp sensor in the wall is so the thermostat can sense the temperature of a room away from the location of the thermostat. If you have a unit that is 2nd air ready and your thermostat has multiple zones you should have a wire in the wall already. Do you have a decal anywhere in the room that says something like "temp sensor here"? If you do, the wires should be in the wall but you will have to purchase the temp sensor. My decal was just above a light switch and I removed the light switch to find the wires. I still had a very hard time finding the wires as they seemed to be towards the bottom of the wall. I finally was able to locate them with a bore-a-scope (small camera on a flexible tube) and then I was able to fish them up to the light switch hole with a hooked wire.

[Openingshok]

My Shasta Phoenix 30BH came prepped as well. It actually has the temp sensor on the wall already. I have dropped the roof vent cowling and found the wires where they should be. The OP stated he had to purchase a zone control box. What is that? I would think that would come with the AC. I also have a dual zone thermostat. With 1 AC it only allows zone 1 so when I push the zone button it doesn't change from zone 1. Will it recognize the connection of the second AC and activate the zone 2 feature?

[pirlbeck]

Originally Posted by Openingshok

My Shasta Phoenix 30BH came prepped as well. It actually has the temp sensor on the wall already. I have dropped the roof vent cowling and found the wires where they should be. The OP stated he had to purchase a zone control box. What is that? I would think that would come with the AC. I also have a dual zone thermostat. With 1 AC it only allows zone 1 so when I push the zone button it doesn't change from zone 1. Will it recognize the connection of the second AC and activate the zone 2 feature?

The zone control box is the box that all of the electrical connections connect to. It has circuit board in it and number of spade terminals on it that the control wires connect to. Also, the 120V power feed wires are connected to it.

When you purchase the AC you need the roof unit and then you chose which type of inside grill, which depends on if you want it to be connected to duct work in the ceiling or to just blow the cold air out the grill vents. Also, if you want to add the heat strip it takes a different part number of inside grill as the control box is different to control the heat strip.

I don't think the thermostat will recognize the 2nd zone until the wiring is connected to the control box. The control box has jumpers on it that must be set to tell the thermostat what zone it is. My thermostat could have up to 4 zones.

[Openingshok]

Originally Posted by pirlbeck

The zone control box is the box that all of the electrical connections connect to. It has circuit board in it and number of spade terminals on it that the control wires connect to. Also, the 120V power feed wires are connected to it.

When you purchase the AC you need the roof unit and then you chose which type of inside grill, which depends on if you want it to be connected to duct work in the ceiling or to just blow the cold air out the grill vents. Also, if you want to add the heat strip it takes a different part number of inside grill as the control box is different to control the heat strip.

I don't think the thermostat will recognize the 2nd zone until the wiring is connected to the control box. The control box has jumpers on it that must be set to tell the thermostat what zone it is. My thermostat could have up to 4 zones.

AHH HAA. Thank you! That is good to know. I knew about the unit and the inside air plate, but didn't know about the controller yet.

[John A Donaghy]

Hello, we have a 2021 Flagstaff FKBS and wanted to add a 2nd ac - can you please tell me the parts you purchased and where from? I am pretty sure I can do myself and my FR dealer gave me the "we'll give you the unit we want, for a lot of money, and you'll control from the overhead bedroom inlet fixture" Many thanks in advance

[Openingshok]

Originally Posted by John A Donaghy

Hello, we have a 2021 Flagstaff FKBS and wanted to add a 2nd ac - can you please tell me the parts you purchased and where from? I am pretty sure I can do myself and my FR dealer gave me the "we'll give you the unit we want, for a lot of money, and you'll control from the overhead bedroom inlet fixture" Many thanks in advance

Hey John! It's been a couple years since I went down this rabbit hole but a quick search of emails pulled these parts. We purchased the A/C from one supplier, the chill grill from another and the control board from ebay. The process is super easy. If you contact Tim Herman at Forest River he was amazingly helpful and generous with his time.

A/C cealing grill:8430A6321 - Coleman-Mach ChillGrille Replacement Ceiling Assembly Lateral Ducted

SKU: NTP-41-0101

A/C unit was a coleman mach 3 13.5K

Control Board: Coleman Mach 9430A751

I'm fairly certain all these part numbers are correct. It took some trial and error, ordering and returning to get the right combination so obviously do your research but this should get you started.

[Barneyjoe]

Hello all, I know this post is 2 years old, but I did see some recent activity. I too am installing a second Coleman Mach 15 AC in a 2020 Rockwood that is prewired. I have the infamous thermostat wiring question which is has anyone figured out which wires connect to the red, blue, black and purple ones that are located in the ceiling vent area? Any help would be much appreciated.
Thank you,
Joe

[KSH]

Call Coleman support. They are very helpful.

[bluelinehi]

Just purchased a 26fkbs wondering if the 2nd AC should be added by dealer before I pick it up? How does it cool with just one AC? Thanks in advance.

[NMWildcat]

Originally Posted by bluelinehi

Just purchased a 26fkbs wondering if the 2nd AC should be added by dealer before I pick it up? How does it cool with just one AC? Thanks in advance.

Is the existing a/c 15k or 13.5? What outside temps are you expecting to camp in? Are you going into the SW summer where the temps might be 100°+?
If you think you need 2 air conditioners, now is the time to add it if they can get one.

[bluelinehi]

We AC is 15000, not exactly sure where our travels will take us at this point so I think I’m going to add it. Any thoughts on a second max air in the living space? It’s only 200 for dealer to add it I kinda thought at that price compared to the purchase price it’s a no brainer.