What does the light switch in the panel do?

[skater]

In my 1991, it switches between the air conditioner and microwave; you can't run both at the same time. Wanderlost (who has a 1996) and others have reported that this switch controls the outlets in general. See this page for different examples.

It'd be nice if it were labeled, but in mine the air conditioner is up and the microwave is down, which is easy to remember because it points in the direction of the appliance it's giving power to!

Why is this? Believe it or not, Airstream did this in a lot of campers in the late 80s/early 90s; my parents' 1986 34' triple-axle trailer has something similar. I believe it was done to save wiring for more than 30 amps of power in the camper. Now, 50 amp service isn't unusual at campgrounds, but I think back then 30 amps was the norm.

[reday]

I am going to have to really look at this. The other Airstream (the motor home) was 30 amp and you could have the AC and the microwave both going at the same time... no switch like on the B190. Now, if you had the TV on too, it would probably pop the breaker.

Is there a collection of wiring diagrams - AC & DC available for 190's?

I did upgrade the motor home to 50 amp so I could run both AC's at the same time. I still have to manage the TV/microwave/AC for one leg, but I can run two out of the three at a time and feel like I should be able to figure out how to do the same on the 190 and do it safely.

[skater]

I am going to have to really look at this. The other Airstream (the motor home) was 30 amp and you could have the AC and the microwave both going at the same time... no switch like on the B190. Now, if you had the TV on too, it would probably pop the breaker.

Is there a collection of wiring diagrams - AC & DC available for 190's?

I did upgrade the motor home to 50 amp so I could run both AC's at the same time. I still have to manage the TV/microwave/AC for one leg, but I can run two out of the three at a time and feel like I should be able to figure out how to do the same on the 190 and do it safely.

To be honest, I think you can do it safely, but it probably does exceed code somewhere.

Here's why: The converter is a 32 amp, which means it draws (at a max) 3.2 amps at 120 volts. Thus you have a 15 (or 20?) amp circuit devoted to something that's drawing a maximum of 3 amps. Now if you do like I did and upgrade to a 60 amp converter, that's still a max of 6 amps at 120 volts (and that's a MAX - I don't think you'd ever actually be able to use that much, there simply aren't enough devices in the camper).

I haven't run the numbers for the A/C unit, but it's only an 11,000 BTU model, so it definitely draws under 15 amps. I know you can start and run the A/C off the 2800 watt generator with a 1000 watt base load. I haven't done any numbers for the microwave, though.

I have this with a rough diagram of the electrical systems, but it's probably not telling you anything you don't already know (since you already have another motorhome).

Unfortunately I don't know of any wiring diagrams, but I'd love to get my hands on a set. I have this that may provide some clues, but of course it's based on mine and yours is probably different. I wouldn't mind slapping Airstream around a little bit for some of the odd wiring decisions they made, though. (I need to update that page - the flickering of course was due to low voltage, and the unknown wire that goes into the engine compartment probably goes to the generator...)

[reday]

Both of those posts are really helpful. Will get around to seeing what can be done... if anything.

Other fish to fry first.

Sincerely,

[reday]

OK, I looked at the AC panel on the 190 and the motor home. Both have a 30 amp main. The MH then has a series of 20 amp breakers for the other circuits with the AC and Microwave on separate circuits. As I mentioned, the only time I have trouble is when the TV is on (separate 20 amp circuit) and something else kicks in (like the water heater on its own separate 15 amp circuit). Then, the 30 amp main kicks out.

So, it would seem to me that if the 190 had been wired with one more set of breakers in the blank space that I have, then a separate line could have been run to the microwave and eliminate that dumb switch.

BTW, I'm going to have to rewire or turn over the switch. The common sense up for AC down for MW does not apply... mine is backwards.

[skater]

BTW, I'm going to have to rewire or turn over the switch. The common sense up for AC down for MW does not apply... mine is backwards.

Sorry. Sometimes it seems like the guys on the assembly line just did whatever occurred to them that day. Which may be the case - I'm sure they're building trailers every day, but B190s were certainly less common (assuming they were done at Jackson Center with the trailers) and probably more prone to variation.

[reday]

While trying to start the generator today I noticed something. The AC breaker on it is 25 amp. It may be that is the reason for the switch. When you are hooked to shore power the 30 amp breaker could handle both the air and the micro wave, but when the genset is powering things, it is limited to 25 amps output which is not enough for both - along with the Univolt.

Thus the generator is limiting factor for the rig... If power automatically switches over to the generator and both AC and microwave were on, it would then trip the 25 amp breaker outside on the generator... that would be a pain to deal with every time it happened... thus the switch.

If only Onan had built a generator capable of 30 amps in a size that would fit the B190's - all this would have probably been unnecessary.

Does this make sense?

[skater]

While trying to start the generator today I noticed something. The AC breaker on it is 25 amp. It may be that is the reason for the switch. When you are hooked to shore power the 30 amp breaker could handle both the air and the micro wave, but when the genset is powering things, it is limited to 25 amps output which is not enough for both - along with the Univolt.

Thus the generator is limiting factor for the rig... If power automatically switches over to the generator and both AC and microwave were on, it would then trip the 25 amp breaker outside on the generator... that would be a pain to deal with every time it happened... thus the switch.

If only Onan had built a generator capable of 30 amps in a size that would fit the B190's - all this would have probably been unnecessary.

Does this make sense?

Yeah, it makes a LOT of sense. That never occurred to me. Thanks!