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Topic: AC/ generator question (Read 667 times) previous topic - next topic

AC/ generator question

Kind of a Long winded 2 part deal, I’ve got a 99 U320, 12kw powertech generator, and 3 newer-ish domestic air conditioners (I’ve had this coach for just over a year, they were supposedly new a year or so before I bought it) had a bearing go out in the generator head, replaced that, and the generator was putting out 175 volts. I slowed the engine speed down until it was putting out 120. Not sure if that messed with the wattage/amperage output because now none of the ACs will produce cold air. Worked fine for a couple of weekends, now just the fan runs, and what sounds like the compressor trying to start. I’ve ordered a replacement voltage regulator and going to put the generator back to the correct RPM, but what could I have screwed up in the AC units? I’ve read that they are problematic, but I’d have a hard time believing all 3 would fail within a week without some sort of outside interference.
1999 U320 4200 DGFE

Re: AC/ generator question

Reply #1
I'm not a expert on this stuff, but I believe the generator has to run at a specific RPM (usually 1800 RPM on big units).  If you adjust the engine speed the output voltage will change (as you observed) BUT the output frequency (Hertz) will also change.  The frequency is supposed to be very close to 60Hz.  If you alter the frequency (above or below 60Hz) it can cause problems.  Not good.

You can buy a inexpensive meter that will tell you (among other things) the frequency being put out by the generator.  Just plug into any outlet with generator running, and push the appropriate button on the meter.  These are usually sold at Lowes, Home Depot, and other places.
Highly recommended tool to carry in your coach - many uses!

Kill A Watt Meter - Electricity Usage Monitor | P3

Hopefully, a more knowledgeable member will respond to your question with more/better info.
Chuck, Jeannie & Bella the MalChi
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Kia on a Kar Kaddy SS
I may suffer from the Dunning-Kruger effect, but I seriously doubt it...

Re: AC/ generator question

Reply #2
175 volts can take out an AC appliance.  As far as what is destroyed in your Dometic units I would call Dometic and see who they recommend to call.  I've given a link to the following threads as they may give you a better understanding why having an EMS with power shut off at low or high voltage is important between your ATS and the circuit breaker panel to protect you from both your generator and your shore power.

VERY IMPORTANT - 10KW Isuzu generator voltage regulator DESTRUCTIVE PROBLEM

Surge protector woes

https://youtu.be/p4tixm-kn00
97 U295 40, Build #5040, 6C8.3 325 HP
Oregon Continuous Traveler
Samsung Residential #RF20HFENBSR,
Xantrex SW2012, (3) AGM8D, (2)  AGM Grp24 Eng, Victron BMV-712, 1800w Solar 4 LG & 2 Sunpower
Extreme Full Body pt w/hdlmps, all new furn/floor, 4 down Lexus 2004 GX470 AWD curb weight 4,740 lbs
Prev: 1990 Barth, 10L 300 2 yrs; 91&92 Monaco Signature, 10 yrs, 10L C 300 &  6C8.3 300; 1997 ForeT 6C8.3 325 since May 2017.  Employer by Guaranty RV 14+ yrs.  Former VW New Car Dlr/Service Dlr, Sales Mgr, Rv Sales, and Service Adviser from 1968-2017
"Don't criticize what you can't understand" Bob Dylan

Re: AC/ generator question

Reply #3
I will add, as far as I know I never tried to start the AC units with that much voltage. I was checking voltage with the breakers shut off. I turned them back on after I slowed the generator down, so they only saw 120v, but not sure about the rest of the output. The AC units have a total of 8 days or so running in this situation, and the 2 rear ones both  stopped working yesterday. With that being said, I never checked the output before, so it may have been producing the 175v the whole time I’ve owned it, but I highly doubt that. I’ve had no other issues with the electrical, and I spend weekends at a racetrack with the generator running non stop running trailer lights, air compressor, battery chargers, and whatever other things we may need. Has been flawless up until this point.
1999 U320 4200 DGFE

Re: AC/ generator question

Reply #4
That looks like a handy little meter. I ordered one of those too. Thanks
1999 U320 4200 DGFE

Re: AC/ generator question

Reply #5
Sounds like the voltage regulator has failed.  Changing the RPM changed the cycles from 60 to ? because you need a meter to set this through the engine RPM. No way to adjust this by sound.  Now all this rambling brings me to this:  you most likely killed the compressor capacitor in both units due to low cycles. Pull the covers, find the capacitors, and check them for failure. On some A/C units have a combo capacitor that one side is for the fan and the other side is for the compressor.

Mike

Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: AC/ generator question

Reply #6
As a side benefit of this install it incorporates a hertz display for both channels

M2 AC Multimeter - Blue Sea Systems
"Riding and rejoicing"
Bob & Susan
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: AC/ generator question

Reply #7
Start, Run Capactors are sometimes a cause of no start run . They are not expensive and are easy to replace. For less than the price of a Service Call you can but a Capacitance tester, measures in microwave farad symbol uf.
Safe Travels
Dave
2001 U320 40ft
Build #5867
2003 Tracker
VE7DOD

Re: AC/ generator question

Reply #8
Sorry you are working through this problem caused by your generator.

Another point to emphasize is to change gen end bearing before it takes out the several thousand dollar generator end.

Supporting the recommendation for Progressive Industries EMS installed between transfer switch and breaker panel, our EMS cut gen power when a failing voltage regulator increased gen voltage to 170 volts.

Re: AC/ generator question

Reply #9
I’ve ordered a new voltage regulator to hopefully solve the generator issue, and I’ve also ordered the capacitors for the AC unit to try after I get the generator sorted out. I appreciate the help and ideas, I’ll report back with results, good or bad.
1999 U320 4200 DGFE

Re: AC/ generator question

Reply #10
Well, part one of my update, voltage regulator showed up today, and my kill a watt meter. Voltage is now at 119.8, and putting out 60 hertz with the generator at the correct RPM. Capacitors are supposed to be delivered for the ACs tomorrow, and I’m hoping that fixes that problem.
1999 U320 4200 DGFE

Re: AC/ generator question

Reply #11
Well, no luck on the AC repair. Replaced both capacitors, same results. Rear AC compressor hums, and gets hot, but no cooling, and front compressor tries to start, and won’t. Assuming I need to replace them, any direct replacement for a Dometic penguin II? Or just but new of those?
1999 U320 4200 DGFE

Re: AC/ generator question

Reply #12
I just replaced my air conditioners, they had many issues and were 21 years old.  I installed the new Penguin II 15K BTU with the heat pump, the inside filter returns and a new thermostat.  Easy installation and used all of the existing wiring.  Purchased them through PPL. 

If you remove your filter covers and look inside you will see the Dometic unit labels.  Call Dometic 800-544-4881 and give them your unit serial numbers and they will be able to give you the direct replace part number for your coach setup.

Attached is a picture of what I ordered.
John M.
John & Carm Morales
1999, U320, Build 5559, 3600 CAI, Cummins M11 450 HP
"We travel not to go anywhere, but to just go.  We travel for travel’s sake.  Our great desire is to move."


Re: AC/ generator question

Reply #13
Amazon.com: Dometic 651816CXX1C0 Penguin II Heat Pump 15 - Polar White:...

Well, no luck on the AC repair. Replaced both capacitors, same results. Rear AC compressor hums, and gets hot, but no cooling, and front compressor tries to start, and won’t. Assuming I need to replace them, any direct replacement for a Dometic penguin II? Or just but new of those?
2001 4010 U320 build #5865 "Bluto the Bus" since 09/18
2014 Jeep GC Summit Hemi Toad
Full timing since 2016...summers in Western MT, snowbird south winters.
1975 GMC 260 Avion: sold 😥

Re: AC/ generator question

Reply #14
Another update, all 3 of the air conditioners were leaking refrigerant, 2 of them at the joint where the line comes from the evaporator to the drier, and the 3rd unit had a crack in the line about an inch from the same joint. All 3 of them are less than 3 years old, so we decided to at least try to repair them.  We brazed in a service port, repaired the leaks, and charged them back up. 2 of the 3 seem to be working just fine. The third unit either still has a small leak, or a different issue altogether, but I haven’t got back into it yet.
1999 U320 4200 DGFE