Running AC question...

[Sneakinup]

I was told that it is not good to run my AC for long periods of time while the trailer is hooked up to a regular 110 outlet rather than plugged in to a 30 amp outlet. Anyone have any input on that? I used to have an old Class A Southwind and ran the AC that same way. Eventually, it wouldn't run on one of the fan speeds. The tech that repaired it told me it was because I was operating it on too little power. Doesn't sound right to me, but I am electrically challenged.

Thanks in advance for any help!

[overlander64]

It was my experience that one of the quickest ways to burn up the compressor in my '64 Overlander's Armstrong Bay Breeze air conditioner was running it on a regular garage outlet on a 20 Amp dedicated circuit. I had heeded the warnings with every other place where I owned an RV and had a dedicated 30 AMP receptacle installed, but I got impatient during the 6-month wait for an electrician at my previous residence and tried running the air on the 20 Amp circuit and burned out the compressor in short order - - the circuit didn't provide sufficient starting amperage for the compressor so the motor "dragged" on start-up and eventually burned out. The cost of a properly installed 30 Amp RV outlet is cheap insurance when compared to the cost of a new air conditioner. - - The new air conditioner on my Overlander was $750 while the price of the 30 Amp RV outlet installed was less than $100.

Kevin

[Stefrobrts]

I think this answers a question I never asked about why the trailer has a funny plug and campgrounds advertise 30 amp service. Since I don't have AC (or any electric appliances, actually), I have a home outlet (110) adapter on the trailer plug and just plug it in with an outdoor extension cord to keep the battery charged while we're home between uses. At campgrounds I plug it in to whatever is provided. I assume that's all ok.

[overlander64]

Greetings Stephanie!

You are correct in that the main reason that the 30 Amp power source is necessary on a Vintage coach is when it is equipped with an air conditioner or other "high-draw" aftermarket appliances. So long as electric space heaters or other high-draw electrical appliances aren't in use, you shouldn't run into any particular problems utilizing the 15 Amp adapter on your 30 Amp plug (so long as any extension cords used are properly sized and rated) - - a sure sign of trouble is if the adapter is warm to the touch after it has been plugged in for a period of time - - the warmth would indicate a potential overload or possibly internal problems with the adapter. I have such adapters for use at Rallys and always monitor them - - it seems that the newer adapters are only lasting about five years before they crack or show other evidence of wear.

Kevin

[Sneakinup]

Thanks! That's what I thought. I did price out getting a 30 amp line. My trailer sits way back on my property, and my panel box doesn't have all the space necessary. They wanted around $300 to do it. Still cheaper than a new AC!

[Sav'h Steve]

I thought that 20 amps was plenty service if the voltage didn't drop below 108 to 110 volts on startup.

What I had read was that the voltage was the culprit -- ie say below 105. I don't have an amp meter that read that draw to say what it drops to on startup.

Steve

[thenewkid64]

The voltage drop is not an issue if the unit is connected to a 30 AMP outlet. When the voltage drops like you describe you cna create a loop of issues. The higher draw is restricted by the smaller cord/wiring/etc, this leads to an even higher draw that can cause not only the cord to get warm, but causes the compressor and fan to have to work harder due to the reduced amperage, causing more heat. The heating of the cord also causes more resistance in the wire creating more of a voltage drop and allowing fewer AMPS to get through. This creates more heat.

The point I am trying to make is that the excess workload and the heat generated by the low voltage/amperage can cause premature failure of the AC and heating elements in you refer.

The best way I can think to describe it is like when you have a trigger nozzle on the hose, but the faucet is only half open. The first burst is fine, but then the flow lessens. You can get done what you need to but it takes longer and is more work. Same thing here. I can tell the difference when I run my AC on the 30 AMP shore power VS my Genset that needs a tune up. The AC just works better with proper power.

[Sav'h Steve]

Well that got me curious, so I went out to the garage and checked my amps on that line.

It was originally an electric water heater line - 220volts 30 amps to the heater. Since the PO switched out to gas water heat, the line lay fallow. I entended it out to the shop, split it to 2 110s and ran one of those to the 30 amp plug for the TT. My only concern was the length. The 220 line went all the way across the attic, down and out the house to the work shed before it was split. Then it was only a few feet as a 110 line. The extra line I ran was #10. The total length of the run from the main breaker is about 90 feet.

I did install a 20 amp breaker on the sub box in the shed to service the TT. The A/C works fine on startup. It does drop the voltage some on startup but returns to within a couple volts after running a few seconds. I don't notice any heat buildup anywhere.

I just want to be sure I don't do damage to the compressor.

Steve

[thenewkid64]

Steve,

Based on the fact that the wire is a #10 and was originally designed to handle 30 amps you should be fine if you don't pop the breaker. The issue that I see the most is folks running the AC on a 15 amp cord, with a dogbone, plugged into a 20 amp outlet that is shared with 9 other outlets and devices. Lots of line loss and resistance.

Having a proper plug, and proper wire size is important. The overall draw if everything was in use in the trailer would overload the breaker, but just the AC and univolt should be fine.