a/c tripping breaker?

[rebel beck]

On vacation this last week we ran into one problem 2 times. On two nights when I turned the thermostat up it would make a little noise and the breaker would trip, when I went back and flipped the breaker everything would be fine we have the Armstrong unit and everything was cooling just fine, a little much at night. I think it has something to do with the thermostat. Any advice?

[overlander64]

Greetings Becky!

I don't know how common the problem is, but I had similar problems with my Armstrong Bay Breeze before it had to be replaced (I couldn't find any local technicians who would work on the unit). It turned out that the issue was with icing of the cooling unit causing the condensor/cooling fan to drag which would trip the breaker -- once the unit had been allowed to "defrost" all would be well until the cycle repeated itself. The condition most often repeated itself during the over-night hours when the humidity was unusually high in comparison to the air temperature. Unfortunately, I never found a solution with my Armstrong unit before the compressor burned out as a result of being operated on insufficient voltage for a period of about 24-hours.

Good luck with your search for a solution.

Kevin

[rebel beck]

Kevin,
Thanks but I don't think that is it, because as soon as it trips the breaker I go back and flip it back on.

[SafeHarbor]

Hi, Becky,

Does this circuit breaker, by any chance, have a really weak CLACK when you reset it, or does the action have a substandard feel?

I had to replace the A/C breakers in both my Argosy and Excella because they flat wore out. Replacement breakers are less that $10, and your electric supply store may refer to them as "trailer breakers." At least here, it's an over-the-county item.

I also bought an autotransformer to protect the A/C from low voltage campground supply. When the campground gets low, I used to hear the fan slow down and the compressor shudder so hard it shook the trailer. After replacing another Armstrong with a modern AC that I liked less than the sick Armstrong, I want THIS ONE to last.

And as for the often heard lament on this forum that it's hard to find a qualified A/C technician, I have two suggestions. Remove it and take it to them in the back of a pickup. When they look in, they'll see that it's all standard old stuff. The second is go out of the big city and see if you can find an old guy that's worked on stuff of this era in that era in a smaller town. He might just be gratified to take it on once again, especially if he has a creeping suspicion that most of the new stuff is junk.

Lamar

[68 Overlander]

Probably not related but Kevin made me think of it. I have the Armstrong too and it started dragging last week. Turns out the condenser was completely frozen and the breaker finally tripped. The reason was because my intake vents were clogged. I just replaced the filter material last month but used the wrong (Carbon backed) material. I was in denial but I was wrong, it could not breath. Rule out the simple stuff first but admittedly, this is not likely what happened to yours.

[bhayden]

Originally Posted by SafeHarbor

I also bought an autotransformer to protect the A/C from low voltage campground supply.

Lamar,
What type of unit did you get. This sounds like a worth while addition. When I run the A/C at home on a 50' 12GA extension cord I'm down to 112VAC in the trailer. No bad noises but an autotransformer would take the worry out of it.
-Bernie

[SafeHarbor]

Hi, Bernie,

I use a Hughes Autotransformer bought from PPL Motorhomes in Texas. It wouldn't help your case, though. If you have 112 VAC with the air running, the autotransformer won't even be boosting.

Lamar

[SafeHarbor]

And Becky, I forgot to mention that a circuit breaker that's going gets very warm before it pops. If you feel of your breakers and find that one's warmer than the others, I'd bet that's your AC. It'll actually be sort of hot before it goes.

That's because circuit breakers heat up very slowly. They are designed to respond to a direct short and only then will they operate rapidly. For other loads, and the AC is a special kind of load called an "inductive load," it'll respond more slowly. It's the responsibilty of the DEVICE at the end of the wire to have adequate protection for itself - the function of the circuit breaker is to protect the WIRES.

Why is an inductive load (ie, your airconditioner's motors) a special case? It's because they require more current as the voltage decreases, and this additional current makes them HOT. The heat will eventually kill them, and that's the theory behind using an autotransformer when low voltage is present in the campground.

And, this is off topic, but my power pole has been installed and the electrical inspector is supposed to look at it today. I'm having a 200-amp service installed to plug in my two trailers, and it's MINE, ALL MINE.

Lamar

[Inland RV Center, In]

Originally Posted by rebel beck

On vacation this last week we ran into one problem 2 times. On two nights when I turned the thermostat up it would make a little noise and the breaker would trip, when I went back and flipped the breaker everything would be fine we have the Armstrong unit and everything was cooling just fine, a little much at night. I think it has something to do with the thermostat. Any advice?

Becky.

Are you using an extension cord?

If you are, it must be a minimum 10 gauge, or if more than 25 feet, it should be 8 gauge.

As the voltage becomes lower, the compressor will draw more current. When that currect exceeds the 20 amps that you have on your breaker, it will trip, everytime.

The answer, if your not using an extension cord, then becomes low line voltage.

You "MUST NOT" ever, run your AC on low line voltage.

To do so, will burn up the compressor in short period of time.

Lastly, as a circuit breaker starts going bad, it's current handling capacity will reduce, as an example a 20 amp breaker could drop to 18 amps or to even 15 amps., or something in between.

Andy

[Inland RV Center, In]

Originally Posted by bhayden

When I run the A/C at home on a 50' 12GA extension cord I'm down to 112VAC in the trailer. No bad noises but an autotransformer would take the worry out of it.
-Bernie

Bernie.

You have an unacceptable voltage drop for your AC to survive.

Using an Autoformer is an expensive way to fix the problem.

You have a 10 gauge 25 foot cable already on the trailer. If you added a 13 foot 10 gauge extension cord, you would be at the maximum allowable 2 percent voltage drop, with a 30 amp load.

Adding 12 gauge extension cord, even with a load of 20 amps, you must not use an entension cord longer than about 10 feet.

If you wish to use a 50 foot extension cord, and run the AC, you must use a # 6 gauge wire, to minimize the voltage drop.

Keep in mind, as long as the trailer is plugged into city power, the univolt is also drawing some current, that varies depending on the battery condition. It will always draw a minimum of current, even though the battery is at 100 percent capacity.

Certainly, a 50 foot #6 gauge extension cord costs far less money than a 25 ampere autoformer.

Additionally, anyone that has an AC ammeter, will quickly tell you that when your running the AC in your Airstream, as the voltage drops, the currect will increase, which in turn causes the compressor to work harder, which increases the compressor's temperature, and because of that, the compressor works even harder, in turn, drawing still more current.

Any Airstream installed Air Conditioner, should never be run on less than 115 volts AC, as measured at the compressor.

To do so, shortens the compressor's life considerably.

If you had, as another example, a 6 gauge trailer cable (which you don't) and added a 6 gauge 50 foot extension cord, you would still have room left to add another 20 feet of extension cable.

Or putting it another way, to draw 30 amps, a # 6 gauge cable is limited to 95feet. An # 8 gauge cable is limited to 60 feet, a # 10 cable is limited to 38 feet, and a 12 gauge cable is limited to 36 feet, but also to 20 amps.

This information can be found in any electrical code or wiring carrying capacity book.

Andy

[rebel beck]

Lamar,
I think you got it right, we talked to an electrician friend and he said the same the breaker may just be worn out. He is going to check it out for us.
Also I agree about all the campgrounds and there plug ins. Thanks everybody for all the advice and info.

[bhayden]

[quote=Inland RV Center, In]Using an Autoformer is an expensive way to fix the problem.[/qoute]
Wasn't thinking of it only for home use but more along the lines that 108 VAC is all the power company is required to provide under so called "normal" operating conditions (i.e. +/-10% of 120VAC). Ma'n'Pa Campgrounds are likely to be strained on a hot summer day given that many have probably never been rewired since the 60's when AC was less common and no one had "Radar Ranges" in their trailers. An Autoformer would I presume also be an excellent source of protection from surges and spikes (like when the 5'er next to you trips the 30A breaker because he's plugged in his 50A cord with an adapter ).

You have a 10 gauge 25 foot cable already on the trailer. If you added a 13 foot 10 gauge extension cord, you would be at the maximum allowable 2 percent voltage drop, with a 30 amp load.

I do need to figure out what my amperage draw is. It should be less that 15 amps as the main breaker going into the trailer is 20A and at home I'm on a 15amp circuit (20 amp circuits have the "goofy" sideways prong). I haven't figured out what the BTU rating is on my '78 vintage Argosy but I'm guessing 7500BTU; certainly far less than the 13,000-15,000 common on the new units.

The AC power panel in the trailer needs to be reworked. I'm all but certain it's been hack by a PO. The main breaker is a 20A GFI. That's probably OK but it should probably be 30A for future expansion. In series with the GFI breaker is another standard 20A breaker which also controls everything. Then there's one more 20A breaker that controls only the Air Conditioner. Haven't check wiring to the AC but it wouldn't surprise me if it's only 14GA. Since the house breaker doesn't trip 14GA may be OK if the breaker for the Air Conditioner is replaced with a 15A breaker (12A continuous is all you're supposed to draw on a 15A circuit). Better would be to replace the wires to the roof which I'd like to do while replacing the likely original 30 year old motor start capacitor.

Any Airstream installed Air Conditioner, should never be run on less than 115 volts AC, as measured at the compressor. To do so, shortens the compressor's life considerably.

On the "to do" list is wire in a proper 30A recepticle on the side of the house for the trailer. I haven't confirmed the voltage drop yet but I think I'm getting ~2.5V because of the cord. If true I'll still be luckey to get 115VAC at the trailer plugged in directly (I'll be running 8GA wire from the main panel about 5-6' to the 30A recepticle). That's just the way it is; I think they ran #6 (maybe #4) from the pole to the meter which is ~150'. It'll be a lot worse than that at most campgrounds up in the mountains.

-Bernie

[Inland RV Center, In]

Bernie.

The main breaker in the breaker panel, must be 30 amps.

Additionally, the other 2 or 3 breakers, as the case may be, should all be 20 amps, one of which should be a GFI, or even a 15 amp GFI.

Since your breaker panel has been modified, you might start out confirming the size of the city power cable.

If in doubt, replace it with a known cable rating.

Instead of the US 25 foot cables, we have been supplying the Canadian 36 foot cables. That extra 11 feet seems to help most owners.

Seems to come in handy, especially at a rally.

Andy

[bhayden]

Yep, replacing the supply cable would be a good idea too. Turn the old one into a 20' extension cord if it looks legit on inspection. 36' would be a good length. That way even if the power pole is at the "wrong" end or side it should be reachable without adapters/extentions. The only thing to check would be that it and the sewer hose still fit in the rear bumper stowage area.

I've mixed feelings about a plug in vs. hard wired cord. Plugs are notorious for corroding and being a source of voltage drop. It also becomes a more convenient target for theft. On the other hand you can have a couple of lengths and never have to deal with excess cord and the hassle and voltage drop associated with "extra" laying around.

Was AS really using GFI adapters way back in '78? I know it's a good idea now but I didn't think they took hold until about 10-15 years ago.

Then there's the 35 year old house wiring to deal with

And to think, here I am trenching the street and it all started so I could run my trailer AC on hot summer day back in '06

-Bernie