Yesterday I decided to do some work on the 5er, having it parked at my residence. When I turned on the a/c the volt meter showed voltage around 105. Turned the a/c off and killed the power to the unit. Then checked the electrical connections for tightness...they were okay. I did discover the "dogbone", 50 amp to 30 amp I was using had one side which had been very hot and the cord felt hot. I replaced the "dogbone" the turned the power and a/c back on. The voltmeter showed 109, the a/c was runnning and sounded great. I stayed there and watched the voltmeter for about 10 minutes and all was well. I left the unit and when I returned, the a/c was barely running and the volt meter was below 100. I turned the a/c off and the voltage jumped back to 119 and what lights were on became much brighter. I am wondering if the problem could be the start capacitor and how does one check it.Thanks for your thoughts!

It does sound like a bad connection. Are you plugged into a 30 amp receptacle at home? That is normally a good thing. Even if plugged into a 30 to 20 amp adapter, the A/C alone should work normally, I did that for years while living at a house inside my RV. Put a load on your RV electrical system, I suggest not using the very expensive to repair Air Conditioner. You could microwave some water, or run a 1,500 watt heater (my choice). With the heater or microwave running, check the voltage drop. Say it drops from 119 to 115, this is basically normal, and acceptable for the three electrical cord connections with a 10 amp load, the 4 volt drop will be about 40 watts, making a small amount of heat in the cord, and it's connections. However if the voltage drops from 119 to 109 with a 10 - 14 amps load, then it is to much voltage drop, and one of the connections should overheat enough to identify it. Shut off the heater after running it about 10 minutes. Unplug from shore power, and feel each connection. Feel each cord, touch them just a second at first, it might be as much as 130F, but normal is only about 5-8F above the outside air temperature. If you find one really hot connection, you have something else to replace. If you are using a 14 gauge extension cord, it is to small to run the air conditioner - without a voltage booster. 16 gauge extension cord is even smaller, and will give to much voltage loss at 10 amps.I would run my air conditioner at 108 volts, but not below that amount. I have a volt meter designed to stay plugged in all the time, and it has a large enough digital readout to see it from a couple feet away. You can do a search for "Kill-a-watt" on e-bay and find several vendors - for about $20 - $25 range. Fred.

I would expect the "problem" is with the overall electrical load at your residence. I am guessing your 30 amp outlet is farther away from your panel then most outlets in the house, and while you are running an acnd in the RV if the residential acnd starts, could be electric hot water heater, oven or any other sizeable load comes on you may be "over taxing", amps go up volts go down, the electrical system in your house. Mine does exactly as you describe on hoy days so I have to make it a point not to run the RV air. I also have a long extension cord from the 30amp connection to the RV.

A atart capacitor is that--It STARTS the compressor and is only needed to do that. Once the Compressor is running, it is not needed. Your problem may be a bad compressor or more likely a voltage supply problem. Doug

Thanks for the comments, I think I see possibilities from each of you. Today I went out and turned the a/c on and all was well...I had 113 volts. I did find this morning the a/c was on low fan rather than high. I have learned from this forum that can cause the a/c to freeze up, however I cannot believe mine froze up as our temp yesterday was well into the ninety's. I let the unit run today for 3 hours and recorded the time and what the volts were each time. Never had a reading lower than 109 and most of the time it was 113. Only other item on was the refrigerator.I am wired into the house panel and am roughly 70 feet from the 5er. Don't recall the gauge wire we used but did take that into consideration at the time of installation. Have always been careful not to have too much electrical going at one time and have not had a problem until yesterday. I am starting to believe the suggestion of my being so far away from the house, I may be overtaxing the system.Thanks to all....will advise if the unit repeats yesterday.Weldon

At 100v are you sure the electric water heater was not on?Otherwise I would be mapping out where the system loses voltage at each step from home breaker panel to the RV breaker panel.

Electrical or Air Cond. Problem? | Good Sam Community

11 Replies

Golden_HVAC
Explorer
Jun 02, 2013
It does sound like a bad connection. Are you plugged into a 30 amp receptacle at home? That is normally a good thing. Even if plugged into a 30 to 20 amp adapter, the A/C alone should work normally, I did that for years while living at a house inside my RV.

Put a load on your RV electrical system, I suggest not using the very expensive to repair Air Conditioner. You could microwave some water, or run a 1,500 watt heater (my choice). With the heater or microwave running, check the voltage drop. Say it drops from 119 to 115, this is basically normal, and acceptable for the three electrical cord connections with a 10 amp load, the 4 volt drop will be about 40 watts, making a small amount of heat in the cord, and it's connections. However if the voltage drops from 119 to 109 with a 10 - 14 amps load, then it is to much voltage drop, and one of the connections should overheat enough to identify it. Shut off the heater after running it about 10 minutes. Unplug from shore power, and feel each connection. Feel each cord, touch them just a second at first, it might be as much as 130F, but normal is only about 5-8F above the outside air temperature.

If you find one really hot connection, you have something else to replace.

If you are using a 14 gauge extension cord, it is to small to run the air conditioner - without a voltage booster. 16 gauge extension cord is even smaller, and will give to much voltage loss at 10 amps.

I would run my air conditioner at 108 volts, but not below that amount. I have a volt meter designed to stay plugged in all the time, and it has a large enough digital readout to see it from a couple feet away. You can do a search for "Kill-a-watt" on e-bay and find several vendors - for about $20 - $25 range.

Fred.

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Electrical or Air Cond. Problem?

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