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Author Topic: ac front-rear selector switch  (Read 18170 times)

Gary RV_Wizard

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Re: ac front-rear selector switch
« Reply #30 on: August 02, 2010, 09:20:26 PM »
This job can be done with two SPDT (Single Pole - Double Throw) switches, as in the attached crude diagram. Cost should be under $5.

Switch A controls the distribution of the normal 30A/120v power from the RVs load center (breaker panel), whether it comes from shore cord or generator.  This is the Front/Rear switch.

Switch B controls the power line that comes direct from the generator, bypassing the transfer switch and load center. This is the Generator Rear Switch.

With Switch A in the A1 position, it powers the #1 (front) a/c from the load center
With Switch A in the A2 position, it sends normal load center power to one side of Switch B

With Switch B in the B1 position, power from A2 (the load center) flows to AC #2 (rear)
With Switch B in the B2 position, power direct from the generator flows to AC #2 (rear)

When the generator is on, the auto transfer switch send generator power to Switch A via the load center, so AC #1 can be powered either by shore or generator, as needed. AC #2 gets generator power direct via Switch B.

The solid black lines on the switch represent the usual switch position, the red dotted lines are the alternate positions.

Anybody see any problems with this?  I'd hate to screw up his wiring any worse than it now is! The only thing I don't know without seeing it is how the neutrals are arranged. Might need a double pole switch if they have to be switched as well.
« Last Edit: August 02, 2010, 09:25:55 PM by RV Roamer »
Gary
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John Canfield

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Re: ac front-rear selector switch
« Reply #31 on: August 02, 2010, 10:51:27 PM »
Gary - I think your logic is good.
--John
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Lou Schneider

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Re: ac front-rear selector switch
« Reply #32 on: August 02, 2010, 11:03:08 PM »
The only problem is if you use regular Single Pole Double Throw (SPDT) switches, the neutral is unswitched and remains connected between shore power and the generator.

It's not really a problem in normal usage, but can be if the shore power socket has reversed hot and neutral leads.   The generator's neutral would then be energized by the miswired shore power hot line.  Again, not necessarily a problem if the generator has an isolated neutral,  but if the generator neutral is bonded to chassis ground you'll energize the chassis.

I like the idea of isolating the rear air conditioner wiring and running it to a plug that can be either plugged into a socket connected to the 20 amp output of the generator or to it's own extension cord running to shore power.   Simple and there's no way to cross-connect the generator to shore power.

Gary RV_Wizard

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Re: ac front-rear selector switch
« Reply #33 on: August 03, 2010, 08:58:39 AM »
Quote
The only problem is if you use regular Single Pole Double Throw (SPDT) switches, the neutral is unswitched and remains connected between shore power and the generator.
That was my concern too, Lou.  Need to look at  the original wiring to see if there was a separate neutral for the direct-to-generator circuit. The OP didn't mention one, but he may not have known to look for it either.

Note, however, that when the generator is running, the load center is also using the generator neutral and there is no connection to shore neutral (the Auto Transfer switch assures this). You can't have both at the same time, for obvious reasons.

Gary
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Summers: Black Mountain, NC
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asuperheat

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Re: ac front-rear selector switch
« Reply #34 on: August 04, 2010, 07:41:46 PM »
On mine the nutrals were switched also, I think this is why they used the original switch they did it was one switch kinda like these but a diffrent manufactuer https://www.c3controls.com/cam-switches.cfm I guess you could just get another cam switch. Mine was a CA20 I don't remember the manufactuer but I think it is still at my office. There was a series of jumpers to get the switch to do what they wanted originaly.

asuperheat

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Re: ac front-rear selector switch
« Reply #35 on: August 04, 2010, 07:51:49 PM »
Actualy with a little surffing I think the original switch in mine was a kraus & naimer CA20 A222-600. It shows this as a 1-2 switch and it is 3 poles like mine was, 60 degrees like mine also. Not positive but almost sure thats the original switch in mine.
« Last Edit: August 04, 2010, 08:19:51 PM by asuperheat »

Lou Schneider

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Re: ac front-rear selector switch
« Reply #36 on: August 05, 2010, 12:19:44 PM »
Or take two regular 3-way wall switches.  Wire one on the hot side of the circuit, the other on the neutral, and fabricate a handle to connect them so they can ONLY be switched together.

Sounds kludgy, but if done right will solve the neutral problem.

Ned

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Re: ac front-rear selector switch
« Reply #37 on: August 05, 2010, 01:04:49 PM »
Double pole, double throw switches aren't that hard to find.  Just be sure they're break before make or there could be fireworks :)
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
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ricody

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Re: ac front-rear selector switch
« Reply #38 on: June 26, 2017, 07:57:48 AM »
I have a 94 winnebago sun cruiser with the same issue but mine still have the pulse air model# a/c 1157 aftermarket installed, mine alternates running the front and back a/c while plugged on 30 amp shore power. Front one runs for about 12 minutes then switches to back running for 8 minutes.
I changed mine like 5 years ago, it went bad again but now I can not find a new unit anywhere. Just like previous unit it won't switch between a/cs. Anybody knows where could I find it or an equivalent to it?
Im sure this will take care of your problem as well.

John Canfield

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Re: ac front-rear selector switch
« Reply #39 on: June 26, 2017, 05:50:34 PM »
Welcome. Find an electronics geek, amateur radio operator, etc and present the situation to them. I don't think this would be too difficult to design using a microcontroller, couple of relays and a few miscellaneous components. This would be a way fun project to tackle - I wouldn't mind trying it but we leave in a few days for the summer.
--John
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kdbgoat

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Re: ac front-rear selector switch
« Reply #40 on: June 26, 2017, 08:24:23 PM »
Would a Square D smart relay work for that?
I know you believe you understand what you think I said,
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NY_Dutch

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Re: ac front-rear selector switch
« Reply #41 on: June 26, 2017, 08:52:04 PM »
I don't know how Winnie wires the front/rear A/C switch, but here's the way our previous Coachmen was wired. The diagram includes a mod I made that allowed me to plug the front A/C with an extension cord plugged into the shorepower's 15/20 amp utility outlet when the rear A/C was selected and powered by the 30 amp shorepower. With the setup shown, removing the selector switch and hard wiring both A/C's to the 30 amp side would create a direct back feed through the generator's 20 amp breaker, causing it to trip. The ATS does not switch that leg...
Dutch
2001 GBM Landau 34' Class A
F53 Chassis, Triton V10, TST TPMS
2011 Toyota RAV4 4WD/Remco pump
ReadyBrute Elite tow bar/Blue Ox base plate

John Canfield

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Re: ac front-rear selector switch
« Reply #42 on: June 27, 2017, 07:52:47 AM »
Wow, I wish Winnebago would make block diagrams of the electrical systems - it would make troubleshooting/mods so much easier. I think our latest OP wanted an automatic switch arrangement, making a manual switch setup would be pretty easy.
--John
2005 Horizon 40AD, 2006 Jeep Rubicon Unlimited
Our Horizon projects
Our weather

NY_Dutch

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Re: ac front-rear selector switch
« Reply #43 on: June 27, 2017, 07:59:38 PM »
John, an automated system that would allow running both A/C's when the generator is running but only one on shorepower could easily be done with a relay that duplicates the switch action, but a manual selector switch would still be needed for front/rear choice on shore power. Replacing the original OEM switch with a similar one would likely be the simplest solution.
Dutch
2001 GBM Landau 34' Class A
F53 Chassis, Triton V10, TST TPMS
2011 Toyota RAV4 4WD/Remco pump
ReadyBrute Elite tow bar/Blue Ox base plate

 

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