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Old 05-19-2022, 05:51 PM   #1
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Humming Noise

1993 Pace Arrow 32 ft. I have it plugged into 115 volts from my house for the last few years with no problems. Went out the other day and there is a strange humming noise coming from the rear end of the RV. I unplugged the 115 Volt cord and the humming stopped. Plugged it back in and got the humming again. I don't have any electrical schematics. Does anyone no what might cause the humming? I think it might be coming from the converter. if someone has or can tell me where I can get a copy, it would be appreciate it.
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Old 05-19-2022, 06:28 PM   #2
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Depending on power source my ATS ( Auto Transfer Switch ) will hum .

Do you know if your coach has an ATS ?
Do you have a gen set ?
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Old 05-20-2022, 12:50 AM   #3
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I have a 4K Owen Gen set and an auto transfer switch. Like I said it's been plug in at my house for a few years and never hummed until now. the humming is coming from the rear of the RV on the drivers side.
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Old 05-20-2022, 05:31 AM   #4
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Sounds like the transfer switch. Mine buzzes (hums) too.
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Old 05-20-2022, 03:24 PM   #5
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Inverter on?
To test the ATS, disconnect shore power and start genset to power the MH. It is not unusual to find a loose connection in the ATS either Be sure to disconnect shore, inverter and genset power before checking the ATS for loose wire clamp screws. While power is off, check wire clamp screws in the main breaker panel too.
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Old 05-20-2022, 03:42 PM   #6
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Check for loose connections in both your transfer switch and while you are at it, your breaker panel too. Should be part of an annual inspection/maintenance.

Sometimes a transfer switch will start humming because the relay contacts are dirty or pitted. If the relay can be opened a light cleaning of the contacts should stop it. Also some relays have a dampening coil which is to stop the humming and if this coil goes bad the relay will hum. If the contacts are clean and the dampening coil is bad, there's no hazard, just a hum. Some relays can be replaces, and some you have to replace the entire transfer switch.
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Old 05-21-2022, 05:47 AM   #7
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Humming Noise

I unplugged the 115V shore power when I heard the buzzing and haven't plugged it back in yet. Didn't want to plug it back in until I found out more about what could be wrong. I'll connect to shore power again and see if I have any 115V or 12V in the RV. I'll try to check the transfer switch if I can find it. I don't have any information on the electrical system to tell me where it is. I'll just follow the buzzing. If anyone has or knows where I can get a schematic from, I'd appreciate the information. Before I start poking around in the electrical circuit I'll be sure to disconnect any voltage source. Ill post what I find out and thanks to Skip426, nehog, Ran,IN and astrnmrtom for your help.
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Old 05-21-2022, 01:46 PM   #8
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Mine will make noise at times when connected to shore. Normal. If your interested in cleaning the contacts be sure and disconnect the batteries, shore power prior. use an electrical contact cleaner such as...

CRC QD Electronic contact cleaner and follow up with
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