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Author Topic: 2 AC units on 50 amp  (Read 768 times)

DearMissMermaid

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2 AC units on 50 amp
« on: February 23, 2018, 10:02:35 AM »
I am trying to sort out the two AC's in a 1992 Holiday Rambler 5th wheel

It's 50amp
Both AC's are in the living area
Both are ducted in the ceiling
Both have thermostats on the wall
Each thermostat is different but both are Duo Therm

The aft AC has thermostat on living room wall and works, it is ducted in the living area
The forward AC is actually in the living room too but the ducts from it are in the bedroom
The thermostat is in the bedroom

I can run the aft AC and cool the living area but nothing reaches the bedroom which gets pretty hot, so if I nap in the daytime in there, it's just way too hot.

The forward AC won't come on unless the aft AC is on.
Even then it seems not to work right. It cycles on with the fan for a minute or so, then goes off again
If I turn the aft AC off, then the forward thermostat AC won't come on at all

I was hoping to be able to run the AC's independently, not having to have both on.

If it's hot at night, I can see cooling the bedroom but no need to cool the living area since I have pocket doors and generally it's cooler at night, but this is a vintage rig and the ceiling in the bedroom is much lower than the rest of the rig. A hallway bath with wood pocket doors separates the living and bedroom area. No vents in the ceiling in the hallway there.

The former owner is not available so I've had to plow through manuals and do tons of guess work on how things operate. He was in hospice dying when I bought the rig from his grown daughter who knew nothing about anything.

It seems odd to me that the fwd AC won't come on unless the aft one is on too.

Can a 50amp handle both at once?

I guess in the end I need a repairman since I can't conjole the forward AC to come on and stay on.

I was going to replace the filters with clean ones, but when I pulled the filter cover off the bedroom AC a wire that is taped off came dangling out so I stopped right there. I don't care to mess with unknown wires like that.

Any help and enlightenment is appreciated.

THANK YOU!




« Last Edit: February 23, 2018, 05:17:36 PM by DearMissMermaid »
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Living, working. playing  in a 1992 Holiday Rambler Imperial 36' 5th Estate, formerly 8 years 24/7 in a Class C, 1994 Tioga Montara, 28'

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Ken & Sheila

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Re: 2 AC units on 50 amp
« Reply #1 on: February 23, 2018, 11:40:12 AM »
50 amp can handle both ACs. I don't understand why the living AC has to be on t=for the BR AC to come on -- Unless this Fifth was converted from 30 to 50 amp service and the original load sharing device is somehow partially still in the circuit. Normally with a 30amp rig there is either a load sharing device or a switch to power one or the other or one AC is only powered by a generator (or some combination of these).
Assuming this rig was built as a 50AMP, which I think many HR Fifths were, then the two ACs should be totally separate.
Ken & Sheila
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Oldgator73

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Re: 2 AC units on 50 amp
« Reply #2 on: February 23, 2018, 01:02:11 PM »
The AC's must be wired on the same circuit. We had a 1999 Thor 5th wheel that came equipped with one AC in the LR. We had one added to the BR. They were on separate circuits. I could run both at the same time but never needed to. However, could not an AC, microwave and hairdryer. Had to choose two. Your choice is to have them rewired or just run them both when sleeping. As long as your electric is not metered it shouldn't be a problem.
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Ken & Sheila

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Re: 2 AC units on 50 amp
« Reply #3 on: February 23, 2018, 01:45:53 PM »
Go to your main Circuit Breaker Panel. Make sure it is fed by 2 - 50amp circuits, make sure the 2 ACs are on separate circuits. If this is true, then I believe the problem is in the 12 volt controls (thermostats).


ken

Ken & Sheila
2009 Monaco Camelot 42 PDQ
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DearMissMermaid

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Re: 2 AC units on 50 amp
« Reply #4 on: February 23, 2018, 05:30:30 PM »
Yes the rig was originally built as 50 amp

Yes the electric is metered, I own the lot and moved the 5th wheel here in December.

Will study the elec panel and see what else I can figure out.

Orig equipment was Coleman, but these AC are both  Duo Therm Dometics. The papers aren't dated as to when they were replaced.

Thanks for your help and ideas.

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Living, working. playing  in a 1992 Holiday Rambler Imperial 36' 5th Estate, formerly 8 years 24/7 in a Class C, 1994 Tioga Montara, 28'

Pack half the stuff and twice the cash.
http://dearmissmermaid.blogspot.com/

DearMissMermaid

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Re: 2 AC units on 50 amp
« Reply #5 on: February 24, 2018, 07:10:25 AM »
Why is it that people with the sloppiest handwriting choose to label critical things like an electric panel?  ???

The AC's are on separate circuits.

The thermostat may be shot on the bedroom AC.Before it was cycling on/off rapidly now it's not doing anything.

One of those over-engineered digital types with a crummy manual. Nothing comes on now, so grrr... no idea if AC or thermostat.

Someone is coming to look at the AC Sunday. Cross your fingers. Some repairs are quick fast and easy, others require mountains to be moved first.

I've found some strange repairs on this rig, some had to be undone and redone correctly. In some cases it seems they went out of their way to do it wrong rather than right. I understand some things have to be re-engineered to make them work or to save a bundle of money.

During the ridiculous cold snap in Florida with below freezing temps, I discovered the furnace would not roar to life. I went through the manuals for the furnace and the thermostat step by step and still no heat. I even found help in lugging the huge propane tanks to be topped up.

The electric heat couldn't keep up and I hate being cold and it can cause me a ton of problems for reasons I won't bother discussing right now. 

I was so overstuffed with layers of clothing that I could hardly move. I had counted on having the propane furnace to supplement the electric heat when temps plummet. The rig came with two huge 40 pound propane tanks. While they are a pain in the tush to refill, at least it's enough to run the furnace when needed.

Chased around with an RV tech for a few weeks that kept breaking appointments, not returning calls and I thought oh well everything else was going wrong, so I had little time to worry about it but I was so freaking cold and sick.  I had heard he was good if one could ever get him to show up.

One day he pulled in the driveway out of the clear blue on a warm Saturday afternoon.

I rattled off everything I had tried. He actually listened while zipping around at a frantic pace. In 3 minutes time the furnace roared to life. He thought the thermostat was dead, then he discovered the wiring to it behind an inner wall was dead. Ripping out the wall and remodeling the rig seemed a bit daunting. So he raced around scratching his head while fixing two other problems to other equipment.

Looking in the basement he found one of several 12 volt lights (original equipment). He said he could run the thermostat wire to the light's wiring and the thermostat would work and there would be no need to remodel the rig if I would be happy with that, the end result I would have propane heat at the flick of a thermostat.  He did that, handed me a ridiculously cheap bill and sped out of the driveway.

I had to keep a straight face while he worked and it wasn't easy. I so wanted to die laughing.

He had the traditional butt crack showing the entire time he worked.  ;D

We had another serious cold snap and this time when I got out of bed in the morning,  I was able to supplement the electric heat with the propane furnace to bring the RV up to a livable comfort, then turn off the propane furnace and let the electric heat maintain the temp. Oh my gosh, I was so cozy warm,  I felt like a human being again.

Now if I can just get the AC's sorted out before we get to summer temps which it's been in the high 80's (daytime) all week here anyhow.

Life is goof.
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Living, working. playing  in a 1992 Holiday Rambler Imperial 36' 5th Estate, formerly 8 years 24/7 in a Class C, 1994 Tioga Montara, 28'

Pack half the stuff and twice the cash.
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glen54737

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Re: 2 AC units on 50 amp
« Reply #6 on: February 27, 2018, 07:25:38 PM »
Why is it that people with the sloppiest handwriting choose to label critical things like an electric panel?  ???

it's a rule  8)

It sounds like the thermostat was wired wrong did the rewire fix the A/C too?
That seems to be where the problems are.
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DearMissMermaid

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Re: 2 AC units on 50 amp
« Reply #7 on: February 27, 2018, 09:09:27 PM »
An AC guy came out and he couldn't get the bedroom AC to work but he will be back in a week with a capacitor, though.

He said that might fix it, might not, but it was worth a try.  ;D

One hot day recently I ran the aft kitchen AC then while using a medium size fan to try to push air up to the lofty bedroom because I wanted a nap. Well I was amazed, it did manage to push some cold air up there, enough for my nap.  ;)

I discovered the AC in the kitchen has an auto fan selection. It was nice. It would adjust the fan accordingly so it wasn't full blast all the time. The thermostat did seem to work as I had no need to adjust it once I set it, the round ceiling ductwork seemed to work fine even though it seems like very little air comes out, enough does to give it even cooling in that area.

So being that these Dometic Duo therms look ancient, I was pleased that one is working nicely.
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Living, working. playing  in a 1992 Holiday Rambler Imperial 36' 5th Estate, formerly 8 years 24/7 in a Class C, 1994 Tioga Montara, 28'

Pack half the stuff and twice the cash.
http://dearmissmermaid.blogspot.com/

Dauninge

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Re: 2 AC units on 50 amp
« Reply #8 on: March 03, 2018, 06:26:56 PM »
The tech should have been able to test the capacitor and take any "maybe it is, maybe it isn't" out of the equation.
If the AC works, even when you have to do maneuvers with 1 or the other, then it most likely isn't the capacitor. If the capacitor is bad, the AC won't work.

I'd get an RV tech out there. Residential and commercial ACs are different than in RVs.
Dawn
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DearMissMermaid

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Re: 2 AC units on 50 amp
« Reply #9 on: March 05, 2018, 06:13:10 AM »
The AC guy hasn't come back.

He only works weekends in this area and it was in the 40's yesterday so maybe he didn't want to fix an AC on the roof in that kind of cold. He is a friend of a friend who managed to fix some other RV AC's in the park, so that is why I was giving him a test run. He hasn't fixed anything yet, nor charged anything, he just did a look see, so no idea how this will finally pan out.

On a hot day, I did run the forward AC and use a desk fan to try to push air up to the lofty bedroom. It seemed to work but no idea how this will work in summer in Florida.

The forward AC is icy cold and works on a wall thermostat, so that much is good news. I didn't have to fiddle with it. I liked that the thermostat had an auto fan function so the fan wasn't full tilt boogie non stop. The funny round ceiling vents attached to the AC seem to put out next to nothing, but they do amazingly work. I guess it's an illusion. I was amazed at how quickly the living area cooled down.

I have an aluminum roof on the 5th wheel, the old motorhome had a patched rubber roof. It was actually patched end to end with eternabond which did an amazingly good job of keeping me leak free and it was much cheaper than replacing the thin rubber roof.

I still have some time to get the 2nd AC sorted out. Just that I am fixing so many things at once, trying to juggle an efficient budget.

Overall, this 5th wheel even with my repair costs added to it, is still a huge comfy bargain. I feel very lucky. I had investigated hundreds of rigs before finding this one. Most that had all the options and room this had were priced at 4-5 times the original cost of this one.
http://DearMissMermaid.Com

Living, working. playing  in a 1992 Holiday Rambler Imperial 36' 5th Estate, formerly 8 years 24/7 in a Class C, 1994 Tioga Montara, 28'

Pack half the stuff and twice the cash.
http://dearmissmermaid.blogspot.com/