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Topic: RVAC Central Air Conditioner  (Read 4496 times) previous topic - next topic

Re: RVAC Central Air Conditioner

Reply #40 –
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 –
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 –
Quote from: Lon and Cheryl –
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 –
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 –
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 –
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 –
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 –
Quote from: Chuck & Jeannie –
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 –
Buy the board. 

Re: RVAC Central Air Conditioner

Reply #49 –
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

Re: RVAC Central Air Conditioner

Reply #50 –
Hannah and Tyler, hope you are able to get your AC working again. The basement mounted unit must be very quiet.  There are at least 2 oddball Foretravels in existence now yours and mine.  I wanted to post a link to what I did but do not know how.  Search the forum for 1996 U270 Dual Central Air Conditioning.  What I did will not help with your problem.  I agree with what Tom said about relays, capacitors, thermostats, etc.  A good AC tech should be able to get it going if you can not find a board.  In case anyone is wondering my setup is still working, only trouble was a capacitor that needed to be replaced. 

Re: RVAC Central Air Conditioner

Reply #52 –
We took a few days off, now we're back at it!  Going to be doing some research on some of the suggestions of building something to control the unit without the board.  Got a friend who understands the electrical a lot better than I do to help.  There's a good chance it'll go nowhere but it sounds really interesting!

Re: RVAC Central Air Conditioner

Reply #53 –
Haven't heard anything in a while from Hannah & Tyler.  Hoping they will see this, and update their progress (I assume) in getting the basement A/C fixed.  Always hate to be interrupted in the middle of a gripping good yarn, and then never find out the ending.

Re: RVAC Central Air Conditioner

Reply #54 –
Hey guys,

A guy on the Newellgurus site contacted us and offered to build a board for us if we'd test it out and give feed back.  He is trying to create a permanent solution for his fellow Newell owners and we'll be able to beta test for him.  Hopefully that all works out, in the mean time we've replaced our entry door exterior latch and installed a trik-l-charge in the engine compartment and we were wanting to have our patio awning replaced but changed our mind after we got the estimate $$.  I went back to work for a while since the house hasn't sold yet, and haven't had much of an opportunity to do much work on the place.  I apologize for letting the ball drop on this thread but we haven't really made much headway.  We do appreciate the continued interest though so thank you for that. 



Re: RVAC Central Air Conditioner

Reply #55 –
The guy that was helping us with the circuit board emailed me this morning to let us know that Newell Coach had finished making their replacement boards for the RVAC 2702 .  I called Newell this morning and they explained how they had the board reverse-engineered to function and appear very similar to the old SCS boards but that they had fixed the weaknesses found in the original and they have already replaced several of their clients old boards with the new version without issue.  They had five left in stock so we ordered one before they ran out, cost for the board was around $632 after tax.  We are from Miami, Ok where Newell Coaches are made so I had my mom grab it today and hold it until we get back to the area in Feb. 

Re: RVAC Central Air Conditioner

Reply #56 –
We have air conditioning again! 

We got back to the tulsa area on Saturday, picked up the new board on Sunday and got it installed yesterday.  The project went smoothly, Newell did an excellent job of making the new board user friendly.  It took a little longer to install than it could have only because I cut out all of the old janky taped and wire-nut splices in the thermostat loom and soldered all of the joints together.  Other than the soldering it was really just plug-and-play.  That being said, I was still a bit nervous flipping the breakers on for the first time haha but there was no flames and everything worked just like it should.  We've got a new Coleman  6636-3441 thermostat on order to replace the slightly burnt original.  After that's installed we'll be good as new!

Re: RVAC Central Air Conditioner

Reply #57 –
Thanks very much for coming back and telling us the good news!  Happy to hear your extremely unique coach is COOL again.  Safe Travels!

Re: RVAC Central Air Conditioner

Reply #58 –
Glad to hear you found a solution to your problem, and although the board sounds expensive, maybe the cheapest solution after all.

Re: RVAC Central Air Conditioner

Reply #59 –
Would like the contact you had for Newell for the replacement.... need one as well