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rear ac intermittent on shore, always works on generator

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Curious issue:

2007 Holiday Rambler Imperial with 3 ac's.  the bedroom ac runs most of the time off shore power, but occasionally fails to start.  When it fails, the fan motor starts but the compressor will not kick on, almost like a bad starts capacitor.  It will sometimes fail to start, but then will start the 2nd or 4rd time it tries.  BUT, if I am running off the generator, the ac always starts.

The rear is the original ac.



thank you.

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you may or may not know this.  The Rear AC is actually controlled by an Intellitec AESS module, probably located under the bed.  It is covered, I believe, in your manual.  This module actually gives power or priority to your washer/dryer.  As long as the washer dryer is not being used or drawing current, then the AESS switches and gives power to the Rear AC.  Sometimes during cycles of the washer/dryer that are in a lull or pause, the AESS will turn on the Rear AC…but if the load or current draw increases, it switches.  If you were doing laundry on shore and not ion generator, that might explain it.

The AESS is a bit troublesome….probably because folks don’t know NOT to try to run the rear AC when doing laundry.


if the above link fails….Google Intellitec AESS.

you can try a simple, assuming you can use wire nuts or swap wires.  TURN OFF THE MAIN BREAKER.  UNPLUG FROM SHORE.  TRIP THE CIRCUIT BREAKER ON THE MAIN GENNY PANEL.

find the AESS.  Either swap the output leads or use wire nuts and connect the Rear AC line (output) to the incoming line.  Then restore power and test,

if that doesn’t cure it and it works flawlessly on the GENNY, the you may have a shore power issue….or a problem in the transfer switch.

That is more involved.  Do the simple test.  If the unit is bad, they are available online and on .Amazon.   

good luck. Keep us posted.

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Followup to my first post.  This is what another member and I discussed and recommend.

First, assume you have an Aladdin.  You need to turn it on and monitor the voltage and current.  Not really conversant on that, but it is there for you to use in trouble shooting.  Read the manual and go to the screen(s) that give you Line 1 and Line 2 Voltage and current.  Keep that set up when you do the rest.  The expert I talked to believes that the Aladdin has a line to your Factory ATS.  That line measures the voltage (and current?) that is going to the Main Panel.

The Pedestal power MAY be the issue....since you say it works fine on the Genny.  But if you have a bad AESS or one with an issue as to a high resistance, that would also need to be resolved or taken out of the trouble shooting.  BUT, they usually FAIL and you don't have ANY AC...so that is probably not the case.  BUT you can wire nut the Black and White and Ground from the incoming AC to the Rear AC line....that takes it out of the circuit.

SO....the first thing to do.  Record the Voltage and Amperage (if displayed) on the Aladdin when on the Genny.  Note which line (1 or 2) and the readings.  Look on your MAIN panel.  There will be a separate (20 Amp...probably) breaker labeled as WD/Rear AC.  NOTE which LINE # (1 or 2). 

NOW....kill the Genny.  Go to SHORE power.  Turn on the REAR AC.  Record the Voltage and current for Line 1 and Line 2.  If you see close to a 15 VAC drop or lower in the line to the AC, then your pedestal is not providing enough power to keep or start the AC running.  Your Genny may be in the 125 range....so if the Pedestal AC is 110 or so....then that leads to the NEXT step.

From past discussions, as AC units get older, they get more crotchety....  They require a higher voltage to start them and keep them running when the cycle ON and OFF.  If you have a big gap in the Pedestal vs the Genny, then, odds are, you MIGHT need a NEW starting capacitor.  But, if the AC is old and crotchety, then a new OEM might not work or will have the same issues.  There is a Soft Start control box that many folks have used.  There are YouTube videos on it and the installation is simple, assuming you can climb on the roof and do some terminal crimping and wire it in by the instructions.

You will have to get the model number of your AC and vendor (Probably a Penguin) and do some research and locate an RV HVAC supplier that sells the original as well as the "electronic" assist (Soft Start) kit.  

Read the above topic.  Our own @throgmartin is a dealer that stock and has had his techs install them.  He might be a good resource to PM offline or Call for more Info.....  KEEP READING....

NOW....one thing to look at.  IF you have a FAKE 50 Amp service.....you can tell it by looking at the amperage.  The Genny is a TRUE 240 VAC unit.  SO, if you record your numbers and the Amperage is way higher, then that pedestal may be a FAKE.  That means it has 120 VAC on each line.  BUT, if you measured the L1 to L2, it would be ZERO or NO Voltage.  But, if you measured your Genny L1 to L2, that would be 240 or so.

Finally.....if there were loose connections in your ATS and the incoming power terminals (Shore) were loose, you could have a voltage drop there.  With the SHORE unplugged and the MAIN breaker on the interior Panel OFF (50) and the Genny Breaker - Up front on the Genny....OFF, you can loosen the cover and then inspect ro burned or discolored or "hot" wires.  It would be a GOOD idea to tighten the terminals also.  That COULD be it.

NOW, while you have the electricity OFF....inspect the Main Panel.  Pull the cover off.  Make sure that the WD/Rear AC breaker is "locked in" or snapped in.  We have had folks that had the breaker sliding down or away....  Compare it to the others.  You can lift the end with the wire....and then pull up or out and then snap or push back into place. 

 NOW....complete the Electrical Preventative Maintenance.  TIGHTEN every screw on all the terminal strips and the breakers while you are in there.  They DO SHAKE LOOSE....when driving.  Any loose connection will result in a high resistance (Dangerous) connection.

That's it.  Let us know what you find out....

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