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

Re: RVAC Central Air Conditioner

Reply #20 –

[Found the following document, which describes what sounds to be pretty close to the system installed in this unique coach.]

I'm not sure how to insert a quote, but that is the same manual that we have for our system.

Re: RVAC Central Air Conditioner

Reply #21 –
Quote from: The Soft Boulders –
I'm not sure how to insert a quote, but that is the same manual that we have for our system.
To "quote" another member's post, just go to the post and click QUOTE in the bottom right corner.  This opens a window where you can type your response.  It is polite to edit the quoted text, so that it is pared down to only the pertinent lines.  This saves bandwidth and makes it easier to read.

Re: RVAC Central Air Conditioner

Reply #22 –
So there are two A/C compressors on the engine.  Hmmm...  The top compressor (the one with the belt) must be the one for your basement A/C.  The other one is the standard unit that would (if it was hooked up) provide the dash A/C.

I still don't understand how the system can run off both the engine belt driven compressor and off shore power.  The diagram in the manual I linked above shows 2 compressors mounted between the condenser and the evaporator.  I assume these are driven by a 110V motor.  So if that's correct, then there are actually 3 compressors for the basement air, and it switches between them?  Very complicated...

Re: RVAC Central Air Conditioner

Reply #23 –
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.  On low only 1 compressor would run, helpful if only 30amp or lower hookups.  Each compressor was on a different leg of the 50amp. On high if the temp difference was more than a couple degrees between set and inside temp then the 2nd compressor would come on.  So your system may have 2 120vac compressors like mine had, but also has a separate compressor run by the engine.  It sounds like your system also used the inverter to run the blower fans on the evaporator and condenser when using the engine compressor.
On the newellsgurus.com site we've been able to source out all parts with the exception of the circuit boards.  Some of the guys there have come up with a great solution that uses relays to get the current off of the boards.  Pretty easy upgrade and should keep the boards working for a long time.  BTW the boards have replaceable components, so if you're good with a soldering iron you might be able to rebuild it.
I really liked the SCS, it cooled great and was very quiet compared to rooftop airs and being a single package it was easy to slide out to work on.

Re: RVAC Central Air Conditioner

Reply #24 –
Quote from: Chuck & Jeannie –
Yes - I don't really understand the compressor mounting location either.  Hoping Hannah & Tyler will post some photos of the engine compartment, and the rest of the components that are mounted under the coach. 
Is it possible a eng run compressor and evaporator in parallel with the electrical ac evaporator ?  I am thinking that to switch engine compressor piping to electric compressor piping, would be a nightmare.
Three separate systems, dash, electric and second engine compressor etc  with electric blower forcing air over engine driven compressor and evaporator through house duct system?

Re: RVAC Central Air Conditioner

Reply #25 –
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 –
Quote from: folivier –
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 –
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 –
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 –
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 –
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 –
Quote from: RvTrvlr –
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 –
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 –
Quote from: Chuck & Jeannie –


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 –
Quote from: RvTrvlr –
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 –
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 –
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 –
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 –
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 –
Quote from: The Soft Boulders –
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.