Trailer Air Conditioning

[Skwrl 56]

Since more than a few skydivers are familiar with trailers, I'm wondering if I might be able to get some thoughts/advice on a problem I'm having with mine.

I've got a 1995 Starcraft trailer at my local DZ. My DZO provides electrical currently through a very long (~120 foot) and probably insufficient gauge extension cord that provides service to my trailer and a neighboring trailer. It looks like that circuit is 20 amps.

Lights and refrigerator work just fine. It was sufficient to power a small space heater.

Yesterday was a hot day, though, and I tried to turn on the AC. The fan spins, but it seems like the compressor doesn't seem to activate. It makes a whining noise, and then blows the circuit breaker. Fan alone seems to be no problem.

So I'm trying to diagnose the source of the problem. Is it likely to be caused by insufficient electrical service (in which case, it could be fixed either by getting better service or a generator), or is it likely that it's just a crappy compressor that needs to be replaced and the lack of electrical doesn't have anything to do with it.

Any thoughts?

Skwrl Productions - Wingsuit Photography

Northeast Bird School - Chief Logistics Guy and Video Dork

[airdvr 198]

I'm not an electrical engineer but I'd bet you've got a big drop on that extension cord. AC compressors have a big draw.

Please don't dent the planet.

Destinations by Roxanne

[rehmwa 2]

thin little extension cords can draw most of the power. A/C's (especially window ones vs. trailer specific ones) draw a lot.

should switch to a very thick gauge camper extension - park it closer to the outlet - and get on a single fuse

...
Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[SethInMI 145]

To throw some numbers out:

16GA wire has a resistance of 4 ohm/1000 ft, so 120ft x 2 = 240 ft of wire or about 1 ohm total resistance, so dropping 1 V per Amp, or 20 V drop at rated amperage.

That is already a lot for a 120 V circuit, but starting a motor involves a temporary high current draw, I will guess in this case 40 A or more, and that means now a 40 V drop through the cord and so not enough voltage is left to get the compressor motor started. Now the high current stays and pops the breaker.

It's flare not flair, brakes not breaks, bridle not bridal, "could NOT care less" not "could care less".

[billvon 2,417]

1) Measure it. Borrow a voltmeter and look at the voltage at the A/C. If it's sagging more than 15 volts you're going to have problems.

2) You probably want a 12 gauge extension cord. It may not solve the blowing out problem but the A/C stands a better chance at starting.

3) Figure out a way to turn everything else off (fridge, lights) when you try to start the A/C.

4) If none of the above works, the more expensive solutions are a more efficient A/C, an inverter/battery to smooth out your load or some local power generation (solar intertie etc.) The idea there is that a few hundred watts of solar might make the difference, and you're only going to need the A/C when the sun is out.

(And for the love of God do NOT just upsize the breaker!)

[wolfriverjoe 1,346]

Has the A/C been run yet this year?
It might be that the compreessor is a bit stiff, and is drawing a lot more current trying to start up than it should. Maybe plug it in somewhere else that won't have the extension cord issues and see if it works properly there.
Otherwise, I'd go with Billvon's suggestions.

"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

[CSpenceFLY 1]

For a run that long you will want a 10ga wire and only one trailer plugged in if you are going to rune the air. If you have a very strong circuit you might be able to plug both in if only one is running the air.

Your best bet would be to invest in your own cord and if there is room in the breaker box install a 30amp breaker to service your camper. If your going to leave it put a standard 10-3 solid wire will do. If you are going to travel with it you are better off with stranded wire because you can roll it up and it carries more current also.

[CSpenceFLY 1]

BTW, running on low voltage will fuck up your shit.

[Skwrl 56]

Thanks for all of this; all very useful information.

What I'm planning to do is get a portable gas generator and hooking it up directly to that. It should allow me to figure out if it's a local (compressor unit) problem, a more fundamental problem with the electrical service, or both. I'm currently betting the compressor will be able to start up with that generator, but we'll see.

Skwrl Productions - Wingsuit Photography

Northeast Bird School - Chief Logistics Guy and Video Dork

[davelepka 4]

Quote

What I'm planning to do is get a portable gas generator and hooking it up directly to that. It should allow me to figure out if it's a local (compressor unit) problem, a more fundamental problem with the electrical service, or both. I'm currently betting the compressor will be able to start up with that generator, but we'll see.

Without doing any electrical mathmatics, it might be easier to try unplugging everything else from the line (including the other trailer) and running only the AC unit to see if it works.

If you are just overloading the circuit, see if the guy in the other trailer is up for splitting the cost of another circuit, and some better cords.

[Squeak 17]

If all else fails try something like this

You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

[Andy9o8 0]

Quote

Trailer Air Conditioning

I always thought that was a euphemism for shooting out the windows.

[Krip 2]

Quote

Thanks for all of this; all very useful information.

What I'm planning to do is get a portable gas generator and hooking it up directly to that. It should allow me to figure out if it's a local (compressor unit) problem, a more fundamental problem with the electrical service, or both. I'm currently betting the compressor will be able to start up with that generator, but we'll see.

Everyone has a opinion De[ending on how long your going to be at the DZ/

Maybe try shuting everything off except the AC and see if it works. If no workee ther AC might need some gas or a new compressor.

If the AC works Then go to library and get a electrical DIY book and read the instructions about adding new circuit for the AC: UG/10 ga wire in plastic conduit, etc.

Work up a shoping list and price it at Lowes or home depot. If you like the price, install it in the evening when it's cool and the DZO can't see you installing it..

One Jump Wonder

[rehmwa 2]

It really is annoying when you realize that, due to crappy and thin extensions all over the DZ, that most of the power is being wasted just heating up the wrong extension cables. It should be a requirement to use camper quality gauge cords.

especially when breakers trip when people want to use A/C or space heaters

...
Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[SkymonkeyONE 3]

First of all, you are never going to get that thing to work correctly with less than a clean 30 amp service. If you do manage to get your AC to work at all without tripping the main breaker (on a 10 or 15 amp extension cord), then you are in danger of ruining your AC unit. A standard camper top unit costs around $700 when you burn up the one you've got, so be wary of trying to run your AC off that cord.

Chuck

[Skwrl 56]

Chuck,

Given that, and since it's not likely that I can get the trailer closer to the power supply, would you suggest going with a generator? Keep in mind I'm only in it on the weekends (and it's in Massachusetts), so it will probably only be run a total of 16 or so hours per week (8 hours / day).

-Jeff

Skwrl Productions - Wingsuit Photography

Northeast Bird School - Chief Logistics Guy and Video Dork

[normiss 622]

Unless you get the expensive, super quiet generator, you will have some very unhappy neighbors.

[Squeak 17]

Quote

Chuck,

Given that, and since it's not likely that I can get the trailer closer to the power supply, would you suggest going with a generator? Keep in mind I'm only in it on the weekends (and it's in Massachusetts), so it will probably only be run a total of 16 or so hours per week (8 hours / day).

-Jeff

Try a voltage booster

You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

[davelepka 4]

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would you suggest going with a generator?

Isn't that going to be noisy? Are you planning to shut down the AC at night?

See if any of the local jumpers are electritians and can help you upgrade the service and the cables. If not, see if any of them know an electritian who might be interested in a trading the work for a tandem? It would be a cheap way for the DZO to get the service upgraded, and then he could even charge you two another $10/month for the hook-up to offest the rest of the cost.