RVAC Central Air Conditioner

Topic: RVAC Central Air Conditioner (Read 3971 times) previous topic - next topic

Re: RVAC Central Air Conditioner

Reply #25 – August 30, 2018, 04:25:21 pm

I would like to be more helpful with shedding some light on how it all it works, but I think you guys already know more than I do HA! The complication of it all could be the reason why there is only one like it, probably sounded better in theory than in practice.

Re: RVAC Central Air Conditioner

Reply #26 – August 30, 2018, 04:34:27 pm

Quote from: folivier – August 30, 2018, 03:58:06 pm

On my 1998 Newell with the SCS A/C I had 2 separate systems. Each had 2 compressors which was controlled by the hi/lo switch.

So on your Newell setup, I can understand how it would all work on shore power. What about when you were driving down the road? Did you have to run your generator to have any A/C when driving, or did you also have a "automotive" dash A/C system with a engine driven compressor?

I personally don't have any problem with running generator to power the A/C units. That's what we do now. And I can see some advantages to the basement mounting, such as less aero drag from roof projections, and less noise/vibration because you are not sitting directly under the A/C compressor and fan motors.

In the case of the OP's U280, trying to use a 2nd belt driven compressor, and inverter driven fan motors, seems to add a lot of complexity for little gain. Unless the alternator was sized up big enough to cover the battery drawdown, you are just draining your house batteries for no real benefit. Much simpler to run the generator and power the 110V compressor motors directly.

Re: RVAC Central Air Conditioner

Reply #27 – August 30, 2018, 04:52:23 pm

That circuit board looks bad, but I doubt theres much to it besides some relays. Flight systems can probably repair ir for you. They have fixed all sorts of boards for me.

http://m.flightsystems.com

Of course this requires you removing it, getting it to them and repairing the wires to hook it up if they can fix it. Might be easier to cut a hole in the roof and go conventional AC or just replace a roof vent with a rooftop AC.

Re: RVAC Central Air Conditioner

Reply #28 – August 30, 2018, 04:57:03 pm

Appears from his first letter, both engine driven compressors were used for over the road air, but as mentioned, did not work out.
As far as I know Newell's have electric basement or roof airs and separate engine driven compressor dash air.

Re: RVAC Central Air Conditioner

Reply #29 – August 30, 2018, 05:03:34 pm

We're sorry you guys are having such a rough time with your coach. It is not unusual for new owners to make unpleasant discoveries about their newly acquired dream boat. It is why we tell people who come here looking for advice, that they should be prepared for irritating, and sometimes very expensive, problems to crop up. It is just the nature of these vehicles.

Fixing a standard "broken" air conditioner would be so simple. Pull the old one off, drop a new one in. Boom - you're done. Costs some money, but at least you have cold air again and can get on with your journey.

In your case, of course, not so simple. Which puts you guys in a bad spot, and not a lot we can do about it. We really like to help new owners get past their problems, because we know the end result is worth it. If anyone on the Forum can think of any way to help you, you can be sure they will speak up. For now, all we can do is try to understand how your unusual coach functions. We've got some smart people here, and you can bet they are scratching their heads trying to figure a way to help you.

You said Newell is having some new circuit boards made up. Did they say how long until they might be available?

Re: RVAC Central Air Conditioner

Reply #30 – August 30, 2018, 05:22:02 pm

Got the circuit board out, there are no holes burned through it but there is significant damage to some of the components. It burned the AC (alternating current) leg 1 pretty bad and all of the thermostat wires. The circuit leg that goes from the board to compressor 1 is also burned in half.

Re: RVAC Central Air Conditioner

Reply #31 – August 30, 2018, 05:37:07 pm

Quote from: RvTrvlr – August 30, 2018, 04:52:23 pm

That circuit board looks bad, but I doubt theres much to it besides some relays. Flight systems can probably repair ir for you. They have fixed all sorts of boards for me.

We will contact them and see what they can do. Thank you

Re: RVAC Central Air Conditioner

Reply #32 – August 30, 2018, 05:42:14 pm

Thats so severe that I doubt it was a bad connection but more likely a short circuit of soem component. You probably need everything checked before possibly burning up a new board.

Re: RVAC Central Air Conditioner

Reply #33 – August 30, 2018, 05:45:48 pm

Quote from: Chuck & Jeannie – August 30, 2018, 05:03:34 pm

You said Newell is having some new circuit boards made up. Did they say how long until they might be available?

They said that their engineers were working on having some new ones made up and that they should be getting one of the first ones in fairly soon but that they didn't know when for sure and that they didn't know what one was going to cost.

Re: RVAC Central Air Conditioner

Reply #34 – August 30, 2018, 05:55:02 pm

Quote from: RvTrvlr – August 30, 2018, 05:42:14 pm

Thats so severe that I doubt it was a bad connection but more likely a short circuit of soem component. You probably need everything checked before possibly burning up a new board.

We were planning on having the unit removed and completely serviced before it was fired back up if we were able to come up with a solution to the problem. There is no telling how long it has been since it has been cleaned because there is no way to open it up without removing all of the duct work on top of the unit.

Re: RVAC Central Air Conditioner

Reply #35 – August 30, 2018, 06:45:03 pm

Seems to me the unit takes 120 volts via a relay or two to power the A/C, and that with your emergency all could be bypassed and that you could manually turn on the system and be cool. Having a wiring diagram could make it easier. Not sure what the circuit board does other than turning off & on based on thermostat and sequencing fan first, compressor moment later.

Re: RVAC Central Air Conditioner

Reply #36 – August 30, 2018, 09:31:27 pm

Thats what it seems like but without seeing the whole schematic I dont know if it uses multiple cooling loops for the engine driven and AC powered compressors or solenoid valves. Just hooking stuff up could be risky without understanding the whole system and how it functions.

Re: RVAC Central Air Conditioner

Reply #37 – August 31, 2018, 03:40:13 pm

Emailed Flight services a picture of the board, they said the damage was to severe for the possibility of repair. Neither of us really want to do away with the system and replace it with roof units, so the search for a new board continues!

Re: RVAC Central Air Conditioner

Reply #38 – August 31, 2018, 05:30:05 pm

I think you should re-examine the reason you bought the coach.
If you plan on restoring it to like new condition like somebody would for a collector car, go for trying to repair the system with a money is no object philosophy. Problem is, hardly anybody but you will appreciate your effort. It is a one of a kind engineering experiment that Foretravel did. Interesting when new, but now the coach is 25+ years older. What about all the other components in the A/C system. Your system is more complicated than a home central air system, how many of those last 25 years?
If you bought the coach to enjoy, put the novelty of the system out of your mind and move on. Pull the unit and install a couple roof airs, and enjoy your new purchase.
If you bought a Newell or a Prevost you would have a full support system to help you, you didn't, and there is nobody that can help, your on your own.
People will attempt to help you but, its a money pit.
How are the other systems on the coach?
With an older RV you may have other issues to address that may require money and time that you may not want to allocate to the one off cooling system.

I wish you the best.

Re: RVAC Central Air Conditioner

Reply #39 – August 31, 2018, 05:42:27 pm

Quote from: The Soft Boulders – August 31, 2018, 03:40:13 pm

Emailed Flight services a picture of the board, they said the damage was to severe for the possibility of repair. Neither of us really want to do away with the system and replace it with roof units, so the search for a new board continues!

I would join the Newellguru forum and post your problem. Newell used the SCS systems for several years and there are people on that forum that are very knowledgeable on SCS repairs.

Re: RVAC Central Air Conditioner

Reply #40 – August 31, 2018, 09:00:40 pm

That circuit board is mainly an relay switching board and if you are unable to find an replacement I believe you have enough info in that I believe you can rebuild it. I had the same problem with my dash air, one year only, no replacement, no company would look at it and no one had an diagram, least you have one. Link below is what I was up against and without a diagram I got it fix, just a couple relays and a few diodes is all it needed.
Javelina A/C Logic Controller

Re: RVAC Central Air Conditioner

Reply #41 – August 31, 2018, 09:20:30 pm

I found quite a few threads about the SCS basement A/C system over at a forum called luxurycoachlifestyle.com. Thread linked below is typical, and has several posts by a member named "RussWhite". He sounds like a expert on fixing/rebuilding the circuit boards. I think he may also be a member at the NewellGurus forum. If there was some way to get in contact with him, he might be of help in getting your burned up circuit board either repaired, or replaced.

Looking for Newell Coach Basement Air Conditioning Replacement - Luxury...

Re: RVAC Central Air Conditioner

Reply #42 – August 31, 2018, 09:49:58 pm

Quote from: Lon and Cheryl – August 31, 2018, 05:30:05 pm

I think you should re-examine the reason you bought the coach.
If you plan on restoring it to like new condition like somebody would for a collector car, go for trying to repair the system with a money is no object philosophy................................

X2
In 2002, we toured the Newell factory, twice, and we spent a lot of time understanding the detailed differences between a Newell and Foretravel. We "had the itch" and we were seriously looking at options with a hard budget figure in mind. We didn't know what we know today, but we were surprised when three of the Newell staff (sales, service and Engineering) all separately said wait for a used Newell that had IFS and one that did not have the belly (SCS, I assume) AC. Newell had done several conversions to remove the SCS and install roof airs, even then. At that time, the factory conversion was in excess of $6K each unit, and of course was not as clean as a coach initially designed with roof airs.

Even then, basement capacity was of great importance to us and it is even more so today as fulltimers. AC's in the basement and duct work internal to cabinets and in the overhead uses up fulltimers storage space that isn't easily recovered. We didn't appreciate all of that then but we sure do now.

Since that long ago surprise at the factory, I have worked on two Newell's with AC problems and I was further surprised. Both problems required complete removal of the basement AC units to repair. On one, the two AC's were separated units, one fore and one aft in the basement. They had to be completely removed to repair/replace compressors, flex tubing and to be recharged. IIRC, the factory estimate was north of $8K (ea.) for a local authorized dealer to remove, repair, recharge and reinstall, with shipping to and from Miami, OK on each end. Even factory remove and reinstall had an on-site nine-man-hour turnaround time (ea AC). At that time, It was less expensive for the owner to solicit help, to buy two new units and to replace them. It was a miserable, tight job and it took three of us amateurs four plus days to do it. It definitely would have been easier to install two or three rooftop units with remote controls.

I now see little "up-side" to basement AC's, other than someone trying to maintain original design for authenticity's sake. The basement ones I have had experience with are very quiet as compared to roof airs. But everything else is downhill. (serious loss of storage space, long duct runs that compromise cooling effectiveness, not nearly as effective in cooling the coach on a hot day as ducted air in the ceiling, much more difficult maintenance, more complex control systems, flex components that are prone to breaking when trays are extended as well as components that don't age well in highly elevated temperature spaces, even recharges require complete removal on the basement AC's that I have worked on, etc.).

I think Foretravel dabbled with it, in a test bed, but perhaps experienced some of these deficits and the design didn't make it to production. If it were mine, if I were restoring to collector status and money was no object, then I'd go for authenticity. Otherwise, I'd follow the Newell suggestion in 2002 and move to a roof air solution.

Our 42' FT, with three ducted roof airs, that are now 17 years old, had no trouble maintaining 74 degrees inside, all of this summer, always using only two of the three AC's at a time, with outside temperatures frequently above 110 degrees and occasionally above 120 degrees. The Newell that we worked on was a dark colored coach but, at high temperatures, it had trouble getting the coach more than ten degrees below outside temps.....e.g. - inside below eighty degrees when the outside temps exceeded ninety degrees.

Just my take. Sorry you are having these troubles and I wish you all of the best in finding a speedy, good solution.
HTH,
Neal

Re: RVAC Central Air Conditioner

Reply #43 – August 31, 2018, 11:12:24 pm

hi, i own and operate the newellgurus forum and was contacted by one of your forum members about this thread. folivier is a dear friend and has a foretravel now and has had two newells previously and his advise is spot on.

russ white is a member of gurus and the folks on there have been through all of this about the scs basement airs. my 02 newell has 2 basement scs systems each with two compressors. my control boards were redone with new relays preventatively. i also carry a spare. on newellgurus there was a member selling an scs control board a few months ago so you might do a search under parts for sale for scs control board. i can take an entire basement air out of the bay in less than an hour. then the basic things inside are standard compressors fans, etc. any aircon guy can work on them. the biggest pain is that they were originally closed systems so fill ports need to be added. again, any aircon guy can do that easily.

once 4 slide newells became common, they went to 4 roof airs. another thing i take with a grain of salt is how cold folks say they can get their coach. i live in the phoenix area. i assure you in july, you will not get it as cold inside as you would in denver....ha

the way scs did those boards is silly. all the 120v power flows through the boards. so there has been two stages of fixes with our folks. the first it to put better connectors on as one of the failure points is the connections. the second stage is to use external power relays to take the extreme power load off of the board. a fairly simple task and is fully documented on my forum.

previously newell would only sell a board if you had one to trade in since they were just getting them rebuilt. i agree with the folks who looked at your board in that some of the traces on the board are very likely compromised.

i believe newell is now doing a completely new board.

one of our members also has duplicated the board with a breadboard programmed with a microcontroller. but he is just playing with it and it is not ready for others to do. you also have to be pretty handy....putting it mildly

as for the cause of your board getting toasted, it is likely one of 3 things.....1st....a short somewhere in the circuit anywhere between the control board and inside the unit. it could manifest it self at the weakest link which is the board. the board/relay acted like a fuse and blew....

2nd...a loose solder joint causing a short doing the same thing as above. like i said, all 12 amps or so for each compressor is flowing through those wires and the board and associated relay

3rd. a failure of the power relay.

like someone has said, you want to make sure you dont toast another board.

several newell folks have added roof airs and are happy with them. some have them ducted and some just have them just blowing from the grill. wiring can be easily added by using conduit on the roof and running to each aircon and then to a chase near your 120v breaker panel. the basement airs work pretty well. my only critique is they are pretty noisey.

my gang is very helpful and feel free to go over there and ask questions.

thanks as always for the warm welcome you guys have given me.

tom

Re: RVAC Central Air Conditioner

Reply #44 – September 01, 2018, 12:04:22 am

Newell Tom is a great guy and has worked our Forum providing HWH solenoid parts. A good contact for all things Newell. You have come to right place to get your basement aircon working.

Re: RVAC Central Air Conditioner

Reply #45 – September 01, 2018, 12:17:13 am

The ad Tom mentioned is still there in the Classifieds on their forum. It was posted 04-30-2018. It is for one "professionally reconditioned SCS control board", and the seller is asking $500. Since the boards are basically unobtainable, would certainly be worth checking into!

Don't know if this link will work, unless you are a member of their forum (I am):

SCS control board for sale

Re: RVAC Central Air Conditioner

Reply #46 – September 01, 2018, 12:21:56 am

Thank you to everyone for your comments, we are truly blown away by the amount of time and effort that you guys are willing do donate to help us. Since the summer is almost over and the ac is going to be less vital, I would really like to give it a go at fixing it. It will more than likely be more difficult and less cost effective but I enjoy a challenge and my ego for some reason won't let me take the easier route of installing roof units, at least not until we have extinguished all possible solutions. A couple of years ago I rebuilt the transmission from my samurai on our kitchen table, it definitely wasn't the quickest or most cost effective way to go about it because I had to buy a shop press and various bearing pullers along with the parts plus I had to install it, remove it and disassemble 3 times before it was right but the experience was worth more to me than the extra cost. Perhaps I am just a glutton for punishment (my wife says I thrive on suffering) but the only way for me to learn my lesson is to have the wind kicked out of me a few time. Besides, with such a knowledgeable group of folks who are willing to help there's got to be a solution, even if I have to take it piece by piece.

Re: RVAC Central Air Conditioner

Reply #47 – September 01, 2018, 12:34:01 am

Quote from: Chuck & Jeannie – September 01, 2018, 12:17:13 am

The ad Tom mentioned is still there in the Classifieds on their forum. It was posted 04-30-2018. It is for one "professionally reconditioned SCS control board", and the seller is asking $500. Since the boards are basically unobtainable, would certainly be worth checking into!

Don't know if this link will work, unless you are a member of their forum (I am):

SCS control board for sale

It works for me. I am not a member (yet)

Re: RVAC Central Air Conditioner

Reply #48 – September 01, 2018, 12:52:31 am

Buy the board.

Re: RVAC Central Air Conditioner

Reply #49 – September 01, 2018, 09:29:31 am

Tyler, I owned a commercial HVAC company for years. We serviced transport refrigeration as well. I am (unfortunately) very familiar with overly complicated control circuits.

Basic AC systems are very simple. First, the components have to work; meaning the compressor has to run and compress the refrigerant, the condenser fan (outside) has to run and move air, and the evaporator fan (inside) has to run and move air. The compressor will have capacitor and/or a potential relay that will fail. The fan motor may have one as well. These can and should be checked and replaced if needed. I usually replace them anyway since the get weak with age, are inexpensive, and will fail at the most inopportune time.

Next you need a control circuit. The simple circuit is a contactor (relay) to actually connect 120V to the components upon demand, and a thermostat to control to contactor. Typically, the compressor and the condenser fan are controlled by one contactor and the evaporator fan by a second one. This allows the evaporator fan to be on for circulation without cooling.

In your case, I would buy one double pole 20 amp contactor for compressor and condenser fan, one single pole 20 amp contactor for second compressor, and one single pole 20 amp contactor for evaporator fan. All should have 12V coils (for control voltage). You then need a 2 stage cooling battery powered digital thermostat. You will have to pick up 12V to power the control voltage circuit. You have the original wiring schematics so that should not be a problem. Once installed, you have a simple control circuit with readily available components.

TOM

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