Second A/C - Montana Owners Club

Glenn the fifth · 06-23-2014, 04:50 AM

Hello all, I know this topic has been discussed a lot, but without the search function I can't find anything. We have a 2012 3402 and I am finally going to get the second A/C. I am thinking about getting the "Penguin II Low Profile" because I have a somewhat low roof where I keep the trailer in the winter. Couple of questions for those that have been down this path-

1. Should I get ducted or unducted?
2. A lot of the places we stay we only have 30 AMP service, will that be a big issue as long as we don't start the microwave or fireplace with both A/Cs on?
3. Any other low profile recommendations?
4. Should I get one that runs off of the installed thermostat or a "stand alone" with seperate controls in the bedroom? (we won't need it often, but want it when it gets above about 85 or so)
5. I know my trailer is wired for a second A/C in the bedroom, but are there ducts up there also to use?
6. I am fairly "handy", should I attempt the install myself?

Thanks! -Glenn

bethandkevin · 06-23-2014, 05:20 AM

Glenn, we ordered the second from the factory. It is ducted, it is controlled at the main thermostat. All of those provisions should be there on yours I think. If you run both A/C's at the same time, you will be able to run little else. I am able to run them at home, but have not been able to do so many other places. As for installing yourself, I can't speak to it my self, but I believe others have done it and said it wasn't too difficult. If doing it myself, my issue would be that first cut in the roof-I don't know if I could or not!

BusyCarol · 06-23-2014, 05:20 AM

Okay I may not be able to answer all of your questions but I will do my best. My husband and I installed a 2nd AC unit last year on our own. It took us a little longer than someone who does it regularly but it was not that hard. We have a 2013 3100RL and our rig was wired for a 2nd AC and we had ducts. So I am not sure if your unit is the same but I am sure someone will chime in to fill in the gaps.

1. We got the Penguin low profile unit (see answer 3) and we ran it ducted.
2. As for the 30AMP service someone else will have to help you on this one because we only ran ours a couple of times and we were always on 50AMP.
3. Here is the model we ordered Dometic 641815 13,500 BTU Penguin Low Profile Air Conditioner Digital Controls and we also ordered the cover to cover the bottom of the unit because that does not come with one of those.
4. Ours runs off of the installed thermostat and the manual for the thermostat covers how to do that. So check your manual to make sure your unit does dual.
5. This is a bit more tricky. Ours was ducted but depending on the year and when it was made it may or may not be ducted. So before you order your unit I recommend you pull the current cover off and take a look. I called Dometic with our VIN and they told me what unit would work but we also checked to make sure we had ducts first. I think we have pictures of what the ducts look like so you know what you are looking for. I will see if I can find them for you.
6. YES you should be able to do it yourself. The HARDEST PART BY FAR is getting the rig to the roof since it is heavy and awkward! We rigged an extension ladder, leaned against some carpet the we laid on the roof. Then we rigged a pulley system to pull the rig up to the roof. On the roof we had a piece of carpet upside down on the roof so that once the unit was on it we could pull it where we needed it to go. My husband and I put it up there ourselves.

Here are a couple of recommendations that I wish we had known (some simple common sense) before we got started.
1. Make sure you remove all clean sheets from the bed FIRST! Then lay down several layers of towels or something else easy to clean because little bits of metal and other debris go everywhere!!!
2. Check the weather reports...you don't want to get the unit up and a sudden shower goes through or you have a gaping hole in your roof. Like I said ...common sense and luckily we didn't get into any issues with rain but wind was a factor!!!
3. Check, double check, and triple check that you have all of the parts you need BEFORE you begin! For example, the unit does not come with the mounting bolts so you will need to make sure you have the right ones for your install before you start.
4. Everyone helping or in the area should WEAR SAFETY GOGGLES!!!

Hopefully that info gets you started on your 2nd AC modification! I look forward to hearing about your AC adventure! By the way we ordered our rig from rvpartwholesaler.com. They were good to deal with but I don't know if they are still the best price around.

**DQDick** · 06-23-2014, 05:52 AM

We have two full size units and we can not run them both on 30amps. This could mean you could run the smaller unit also, but if so you wouldn't have much if anything left over.

dieselguy · 06-23-2014, 06:23 AM

Like said ... it's a fairly straight forward install. Hardest part is getting it up on the roof. I dunno what configuration of roof vents you have, but why cut another hole in the roof ... remove the current vent in your bedroom, clean up the old sealer and install the new A/C in the hole already there. The ductwork and power was right there next to the original vent hole when I put mine in. I went with the non ducted and thermostat right on the unit as that configuration suited our needs. You'll be pushing things trying to run 2 A/C's on 30 amp. It can be done, but you're putting undue strain on both A/C's even if you turn off absolutely everything else. With both A/C's running on a hot day and only the converter on ... I'm drawing 32 amps. I have the Dometic 15,000 rear unit and a Carrier 13,500 low profile on the front. Carrier offered a good low profile unit ... unfortunately Carrier got out of the RV A/C business in 2011.

Glenn the fifth · 06-23-2014, 06:42 AM

Thanks all. I was not going to cut another hole in the roof. I was planning on installing in the bedroom where the wiring/hole already exist.

BB_TX · 06-23-2014, 07:55 AM

We added a low profile 13.5K in ours. It is non-ducted. I had CW install it as I did not want to try to hoist that thing up there myself. One caution if you do it yourself. When CW first installed it, it would not work. They said it was bad and ordered a new one. When I went back to have the second on installed, a different tech was assigned to the job without being told the details, so he just started checking it out to see why it did not work. Turned out the original tech had tightened the bolts down too tight and it would not allow the fan to turn. He adjusted them properly and the original AC worked fine.

Have never tried running both on 30 amps and don't think we could. There have been a few times we tripped a park 30 amp breaker running just the rear 15K AC along with a few other things like the microwave, WH on electric, etc.

Typically we do not run the front AC except upon arriving at a new RV park on a hot afternoon. Then we run both long enough to cool the trailer before bedtime and then turn off the front AC. Even in the hottest weather the rear AC will keep the trailer cool at night and most of the time during the day.

bigskyjimmy · 06-23-2014, 07:56 AM

No Glen you do not have to cut another hole in the ceiling (NO way would I do that myself)like you said just take the vent out and as far as 30 amp Yeah mine was on non stop all day long down south in a couple of 30 amp only resorts just make sure what else you turn on with it A.K.A. Vacuum,microwave etc..

7.3Ford · 06-24-2014, 02:51 PM

Glenn,

If you want to use the thermostat you have, you have to make sure you get the correct control box. I have a 2010 (which has 5 button), and they went to 12 button a year or two after. Getting the right control box is the most import item here. I had Camping World install mine, since they only charge $120 labor. They put the wrong box in and it didn't work. After three days, they said they need to pull a new wire for the control box, and it was going to be $800-900. I told them to stop, and went and picked up the Montana. I compared the control box in both units, and a little Google, they had the wrong control box. Turns out CW had the correct box, so I took the wrong box back and install it my self.. work fine.

You want ducted unit, so you can run the bedroom unit while at the other end of the Monty, or the reverse at night.

If you have someone to help get it up on the roof, you could do the installation. Bedroom already has wiring, thermostat sensor, duct work, etc. is all there. Just remove the vent in the bedroom, and follow the instructions.

You can run both units on 30 Amps, but you will need to shutdown about every thing else (frig to gas, and converter turn off, if batteries are way down). I have the EMS-HW50C Electrical Management System, which will tell me how many amps are being drawn, and I can manage my load as needed.

I put heat strips in both units, and can run both heat strips at the same time on 30 Amp service.

cdaniels · 06-24-2014, 03:42 PM

We have a 2009 and ours had all the wiring and duct work when the 2nd air was installed. We wanted ours ducted and as Busy Carol said, it doesn't come with the cover or the bolts. You have to make sure you order them with the air and it is a ducted model. If your thermostats has 5 buttons it's not compatible with the new air units. Yours being a 2012 I don't think your unit will have the older thermostat. We got the penguin low profile and it works well.

Benefit of having it ducted, when u only need 1 air during the day u run the bedroom and you do not hear any noise. During evening hours when your trying to watch TV it's a blessing running the bedroom air. Night time you run the living room air no noise while you sleep.

We paid CW to install ours but word of warning, they are hit and miss if they really know how to install ducted. If they don't have the knowledge they tell you it can't be done. We went 3 places before we found someone who knew how to do it correctly.

Good luck, it's well worth it.

cdaniels · 06-24-2014, 03:42 PM

We have a 2009 and ours had all the wiring and duct work when the 2nd air was installed. We wanted ours ducted and as Busy Carol said, it doesn't come with the cover or the bolts. You have to make sure you order them with the air and it is a ducted model. If your thermostats has 5 buttons it's not compatible with the new air units. Yours being a 2012 I don't think your unit will have the older thermostat. We got the penguin low profile and it works well.

Benefit of having it ducted, when u only need 1 air during the day u run the bedroom and you do not hear any noise. During evening hours when your trying to watch TV it's a blessing running the bedroom air. Night time you run the living room air no noise while you sleep.

We paid CW to install ours but word of warning, they are hit and miss if they really know how to install ducted. If they don't have the knowledge they tell you it can't be done. We went 3 places before we found someone who knew how to do it correctly.

Good luck, it's well worth it.

richfaa · 06-25-2014, 02:12 AM

The un ducted ones are noisy in the bedroom had one in the 06 3400 now ducted in the 13 3402 and a huge difference in noise level. Make sure the A/C are on separate legs of the 50 amp service. We run both of ours with no problem. we have seen a total of 37 amps being drawn on the legs
with both A/c running and other normal draws in the unit.

BusyCarol · 06-26-2014, 04:55 PM

I have found this thread very informative regarding the amp draw of running the ACs as a single or dual. Good to know! We are installing solar on our rig next weekend so it is good information! I love MOC!

**DQDick** · 06-26-2014, 05:27 PM

Carol, don't expect to be able to run AC on solar. You can't carry enough batteries even if you could have enough panels and had a big enough inverter. We pull things we supposedly should'nt be able to get away with, but running a fry pan, the microwave and watching tv using the sat dish will dump our inverter without bringing an AC into it. You can guess how I know

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