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Contributor
| Hi all, 1034 here. I'm wanting to upgrade/replace my original 11000 BTU Duo-therm AC units with a single unit. I just would like to hear what other FMC owners have done. I'm not wanting a roof top unit, I think they take away from the sleek streamlined look plus I don't want to cut a hole in the roof. I would like to use the existing cavity with the exterior access door and the existing duct/vent work to keep the interior looking original. The units I have now actually still work but they are overkill, we rarely use both as they will freeze you out. Plus I want something lighter and more energy efficient. I haven't put one of the old one's on a scale yet but guessing they are around 150Lb. each Am also researching some of the 12V units that can be used while barreling down the highway. Thanks, Charlie |
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Contributor
Location: Bluevale, Ontario | Hi Charlie, I have a roof top unit on mine, a 15,000 btu heat pump that works very well. You don't have to cut a hole as it goes into one of the existing 14" vent locations, but you would be giving up the vent. I have lately been looking into alternatives to a roof top unit for my next FMC project because I would also like to keep the roof line clean. I see on Youtube that people are installing small residential mini-split a/c systems into RV's. Seems cost effective and easy to do. The only hard part is finding a suitable location for the condenser unit (don't want to hang that thing on the outside of the coach). Otherwise there are basement model units from the RV appliance makers but they are expensive. Frank #645 |
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Extreme Veteran
Location: Scottsdale, Aridzona | Hmmm . . . . how would I re-invent the wheel ?
The stock FMC 110V AC units are two separate 11,000 BTU units that were also WINDOW AC units typical of the 70s. All the 220V swicth/circuit breaks were there to run TWO OF THOSE UNITS. Nothing else in a stock FMC needs/uses all that power. - http://www.fmcmotorcoach.com/files/Manual/115_volt_air_cond.PDF - Note the RUN amps on page one.
Get under your FMC just aft of the Side Door. See the BIG HOLE in the floor pan ? That is where the air goszina the condenser
See the two sets of louvers in the big door in the lower side of the body just aft of the side door ? That is where the air gosouta the condenser.
The cold evaporator air goes up the two fore and aft sheetmetal ducts inside the closet to the discharge grills above the "pantry" and the passenger side bed.
Visit Home Depot or other fine Appliance Stores near you, and peruse their different WINDOW AC UNITS . . . in particular BTU and AMP ratings. Write down PART NUMBERS of likely units and then get Installation and other Details from GOOGLE on the Nets.
Plan how you would remove TWO WINDOW AC UNITS and replace them with ONE WINDOW AC UNIT . . . in the same compartment of you FMC.
Want to keep the fore/aft high discharge vents or just let it discharge down low right into the hallway ?
Just cut new single BIG hole in wall below closet doors and mount it just like a window Unit ?
What about On/Off switch and other variable controls of the "new" unit ?
But . . . some of those Window ACs also have HEAT ! Oh, my . . . what should I buy ???
But, one 15 Amp new AC means I could maybe have a 15 Amp Micro wave . . . or regular Toaster . . . or Toaster Oven . . .
A little planning in front saves a lot of work and blood and sweat and tears later. THIMK !
Wait till the end of summer when WINDOW AC units go ON SALE at Home Depot or other fine Appliance Stores near you . . . and make your Dream FMC AC Unit Purchase.
Or just ask your Friend who is an AC Man to do it for you.
Cool and/or Heat, Toast, Bake ON !
Lou #120
Edited by hemi354az 2020-06-15 12:24 PM
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Elite Veteran
Location: Victoria, BC. Canada | After you've owned one of these coaches for a while you'll discover one of their glaring shortcomings is a lack of outer storage compartments. Ditching the OEM house A/C units frees-up a nice little exterior storage compartment. I love mine; fit all kinds of crap in there. It even locks!
Then, follow Franks lead and do what Lenny did with his coach, too. Upgrade your alternator, get a 3000 watt pure-sine inverter, increase your house battery capacity (with or without solar) and 'wham-o'... you is going down the road cool-as-a-cat with your barely visible low profile roof-AC unit humming away running off your engine. Or, you can forget all that BS I just said and run it off your genny while you're going down the road.
These new Penguin units are pretty streamlined and far less a 'wart-like' eyesore as most of em'.
https://www.dometic.com/en-ca/ca/products/climate/air-conditioners/r...
I got a killer deal on a big 'wart' for mine so it's going to do for now.
Good luck!
Terry
#846 |
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Contributor
| Hi Frank and thanks for the advice. I've been checking into the split systems as well. Does you rooftop unit work while driving down the road? and if so do you still need at auto AC system, mine has one in the front dash of course but also a rear dash mounted unit. |
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Contributor
| Hi Lou, I should have explained I'm a little further down the road on the mod than I indicated. I've already removed the 2 AC units along with the louvers, etc. have been researching the window unit AC and possibly heat option. I would need to modify the control panel on one of those, maybe remove it, add wiring, and mount it else where. Not sure why I couldn't use the AC duct work for the heat as well. Considering and researching several options right now. I know my coach feels alot lighter minus the old 300lb. combined AC assembly
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Contributor
| The Penguin roof top unit sounds very interesting but could you elaborate when you said it would work while driving down the road running off my engine? Are you talking about engine electrical or the engine mounted compressor? Also I know I'm still learning my way around an FMC but last time I checked my APU aromatically shuts off when I start the coach engine so is there some rewiring that needs to be done to run the AC off the running APU while driving down the road. I'm getting ready to download the installation manuals for some of the roof top Penguin models so will probably answer several of my own questions. I've already removed the units and I agree it would make a large storage area. I've also already removed the 180lb (empty) propane tank along with all of it's black iron gas pipe creating even more storage. Thanks for all the advise so far, Charlie
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Extreme Veteran
Location: Scottsdale, Aridzona | Sorry . . . got the airflow into and out of the House AC Condensers BACKWARDS !
Air goszina the OUTSIDE LOUVERS.
Air gosouta the big hole thru the floor pan under the Coach.
Going, going GONE. Lou #120 |
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Extreme Veteran
Location: Scottsdale, Aridzona | Removed 300 lbs between the wheels and you can feel a difference ? WOW ! I may remove both my bumpers and enter a gymkhana !
Your APU should not shut down when you start the 440 engine.
Typically, since hot air rises, heat vents were located near (or in) floor level, and as cool air falls, AC cooling vents were located high up. But that was in "houses that had basements or some space between the flloor and the ground. Houses in Aridzona are built on a slab, and often SHARE (Heat pumps or Elec AC and gas heat in same unit) ceiling or high on the wall vents for heat and cool. Seem to work OK.
A zillion WINDOW AC units (some with heat) are installed at window height and seem to also work just fine.
That is why I mentioned mounting it (cool or cool/heat) in the hallway just like it is in a WINDOW and Controls on front in the hallway, where they are now, just lower.
Many window units also have a hand held remote "clicker" that also controls.
Wouldn't even have to get out of bed to turn a little heat on before getting up on a chilly morning. Leave the Throne Room door open . . . and the Throne would be nice and warm when you "arrive".
No matter what you end up with . . . don't forget the OTHER WIRING in the closet that is also part of the 110V house AC system.
The engine driven AC units, one at the Dashboard, one in the Bedroom, both rely on the SINGLE AC COMPRESSOR DRIVEN BY THE 440 ENGINE.
They have their own evaporator and condensers and Fans and controls . . . but there is only one engine driven compressor.
Bigger AMP alternator and an Inverter (12V DC to 110 V AC) to run the closet or roof Air Conditioning, that would also run off Shore Power or the APU. Switches for switches !!!
Jump in there . . . . Nikola Tesla and Thomas Edison will be proud of you !
ZAP ON ! Lou #120
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Contributor
| Lew, I was just kidding about noticing the weight reduction of the domestic AC units but don't let me interfere with your bumper plans lol. I'm aware heat rises. Also cold air falls out when you open an upright freezer vs. a chest type. And yes my AC vents are up high and my heating vents are on the floor. In fact that there is no such thing as cold air really, its just air with an absence of heat. And yes one single compressor running front and back, I would have noticed if there were 2 mounted on my engine. I've removed the back unit and starting to take out the front dash units entirely so no need for me to go counting AC compressors at this point. So far the best plan looks like running one or 2 units off the generator when I get the no apu with engine running issue solved. Also researching the more complex inverter driven unit. I do like your idea of using window unit style replacements but I don't plan on waiting until Home Depot clearances them out Fall, Thanks again |
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Contributor
Location: Bluevale, Ontario | Hi Charlie,
My roof top unit runs off the APU or shore power and yes I do run it going down the road. I have removed all the engine driven a/c stuff. Most of the time it cools well but if it's up over 100 deg.ambient it's not up to the task but better than no a/c(that's driving down the road). When parked it cools well even at high ambient temps. Frank #645 |
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Expert
Location: Cottage Grove, OR | If you start the engine before starting the APU you might find that it will then run at the same time as the engine as the voltage drop due to cranking the engine may be what kills it. Reverse the order and see what happens. |
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Extreme Veteran
Location: Scottsdale, Aridzona | Carlos, that front dash heat can put a little heat on your feet, but more importantly, supplies the Windshield DEFROSTER to clear it on the early morning departures . . . even in Mizoura. Zoom ON ! Lou #120 |
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Contributor
| Thanks Frank for taking the time to answer all my questions and for some very good ideas to upgrade modify the system. |
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Contributor
| Appreciate it Stephen, that did it, thanks for saving me alot of time doing needless troubleshooting. I thought a few times it did actually stay running and those few times were probably when I started the APU 1st. I just thought it was possibly a safety feature as this is my 1st motorhome. I have a small cabin cruiser as well and the apu will not run while the boat engine is running but that makes more sense being out on the water. |
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Contributor
| Thanks Lew, and you're right about the defrost, I meant to say I'm just removing all the dash AC components as suggested by a few other members here. I've already removed the rear. I'm leaving the heater core/components and plan to convert all the AC dash vents to heat vents as suggested by someone else here. I don't know what I would do without you and all the other helpful members, some of them experts on this site. |
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Contributor
| Thanks Terry for all the great ideas and suggestions. Rather than go to the shop manual first I go to "mechanics corner", then search all, then all time, then type in what I'm after and its amazing what a data base has been created here. Other times such as this I just ask everyone and have always gotten alot of help without anyone making me feel dumb, thanks again, Charlie |
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Contributor
| I meant started the engine 1st lol |
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Veteran
Location: Olympia, Washington | While you have the dashboard HVAC apart you will notice it has no provisions for fresh air just recirculate. FMC installed two blower fans but no fresh air things that make you go hmmmmmmm. |
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domestic Air Conditioning upgrades
