Only 1 compressor with generator

INSPECTORBOB · 07-08-2011, 01:30 PM

On my 2000 Itasca Suncruiser 35u, the basement air draws about 22 amps while on a/c with both compressors running, but only 1 compressor runs, drawing about 10-13 amps using the Onan 4.8 kva generator. I tried using the generator to run fully loaded running the microwave, coffee pot and portable heater, which combined pull about 30 amps, with no problem so I know that the gen is working, and so is the air, but can't get the air going on 2 compressors using the generator. Suggestions?? Thanks!

The General · 07-08-2011, 06:16 PM

Quote:

Originally Posted by INSPECTORBOB

On my 2000 Itasca Suncruiser 35u, the basement air draws about 22 amps while on a/c with both compressors running, but only 1 compressor runs, drawing about 10-13 amps using the Onan 4.8 kva generator. I tried using the generator to run fully loaded running the microwave, coffee pot and portable heater, which combined pull about 30 amps, with no problem so I know that the gen is working, and so is the air, but can't get the air going on 2 compressors using the generator. Suggestions?? Thanks!

Bob,
I would suggest calling Winnie and fiind out if there is a safety reason why when on gen you can't run both airs. Your gen produces less power than most which are at 5.5KW.
Let us know what you find out!

Steve

Wizard · 07-08-2011, 06:32 PM

Did you check the circuit breakers on the generator itself. Most has one brealer just for #2 compressor and another that runs everything else.

Mine has a 20amp and a 30amp breaker, I tripped the 20 amp once and my #2 compressor wouldn't run.

INSPECTORBOB · 07-08-2011, 08:40 PM

Thanks for the suggestions. With the gen rated for 40 amps, seems it should handle both with no problems. I will check with Winnie on Monday, but was hoping to get it running for the trip home this week-end.

Wizard, I checked both the breakers, and seem to be ok. Is your generator a 40 amp also? Mine is an Emerald 5000+. Problem is I don't know if I have a problem or if this is supposed to be this way, as General suggests.

Thanks

Perry White · 07-08-2011, 09:01 PM

The gen would run both, but it's not big enough to start them. 4kw won't start a 2 1/2 ton AC. 22 amp draw is 2.6kw. ,but it would take 5.2 KW to start it.

INSPECTORBOB · 07-08-2011, 10:06 PM

There are 2 feeds to the a/c control panel. They are labeled "1" and "2". Both are seeing 120v using the generator.
Perry, while using the generator I start out with 13 amp draw, then settle at about 10 amps. Assuming the second compressor draws the same, and it requires 200% running current to start, then it should draw about 36 amps to run #1 and start #2 at the same time, right? (10+13+13). The gen puts out 40 amps, so I am confused!

TXiceman · 07-08-2011, 10:08 PM

Is the generator a 240/120 VAC unit or just 120 VAC. If it is 120 VAC, the power management system is probably keeping 1 A/C compressor off.

ken

David Kanoy · 07-11-2011, 09:38 PM

Inspectorbob,

I have a 2000 Winne Adventure 35U with basement air that came from factory with 30 amp which I converted to 50 amp.

On my unit, before the 50 amp conversion, one leg of the genset was wired directly to the A/C compressor #2. The genset would run both compressors with no problem as long as no other large loads were on.

If you are comfortable with using a VOM, check the voltage on #2 compressor at the basement A/C power connection board with genset running. This power connection is at the lower left bottom of the A/C unit behind a removable metal plate.

Hope this helps,

David

dirko · 07-13-2011, 06:51 PM

Hi Ho: I think WI kind of let people down by not pointing out that the second stage works on a separate winding on the generator. It doesn't register on the one-place because the wire doesn't go through the current sense torroid. The reason is that it is actually out-of-phase with the other stuff.

Anyway, be sure the 20 amp breaker on the generator is set and then be sure you have 120 v. on the second stage when the generator is running.

Dirk

Wizard · 07-14-2011, 06:53 AM

Actually mine is a 6.5kw. It has two breakers on the genny. The 30 amp breaker powers the AC unit and compressor #1, The 20amp breaker powers #2 compressor.

Its fairly east to overload one of the genny breakers by trying to use other devices such as coffee pot as the 20amp breaker also feeds the recepticals in the front of the coach.

dirko · 07-15-2011, 03:54 PM

Hi Ho: Good point Wizard. I can understand why they didn't route the 20 amp through the current sense torroid because it would be out-of-phase with the 30 amp and actually subtract. However, I think you could run the wire through backwards from the 30 amp. and make it work. I've been meaning to try this out but just haven't got around to it.

What do you think?

Dirk

Wizard · 07-15-2011, 06:52 PM

Actually on mine and I think most Winnebagos, when the generator is running, there is no amp reading as the EMS switches over to 50amp mode.

dirko · 07-15-2011, 07:31 PM

Hi Ho: That is probasbly true of the diesel coaches that usually have larger diesel generators. Most of the gas coaches that I've seen stay at 30 amps of the display. If you really had 30 + 20 amps that would be 6000 watts which is more than the generator is rated for.

Anyway we see the current just fine for the 30 amp winding, nothing for the 20 amp.

Is it worth putting the wire through the sense torroid in the wrong direction?

Dirk

FDchief · 07-15-2011, 09:29 PM

Quote:

Originally Posted by dirko

Hi Ho: I think WI kind of let people down by not pointing out that the second stage works on a separate winding on the generator. It doesn't register on the one-place because the wire doesn't go through the current sense torroid. The reason is that it is actually out-of-phase with the other stuff.

Anyway, be sure the 20 amp breaker on the generator is set and then be sure you have 120 v. on the second stage when the generator is running.

Dirk

Yep, that's how mine is wired.

bluepill · 07-15-2011, 09:45 PM

Quote:

Originally Posted by dirko

Is it worth putting the wire through the sense torroid in the wrong direction?

Dirk

For inductive current measurement I don't think that direction makes any difference in AC circuits, just in DC circuits.

mrschwarz · 07-15-2011, 10:07 PM

Actually, on my 30 amp Itasca Suncruiser, the generator is not 240 volts, it has two legs of 120 volts that are in phase with each other. Because of that, the EMS reads the amps from both legs when the generator is running.

If you're only drawing 10 amps, the compressor is not running. If the temperature difference between what the thermostat wants and the ambient temperature is not great enough, the second compressor won't start.

If all the breakers are on and there is voltage at each one, I would begin trouble shooting at the thermostat. Is it calling for both compressors? If it is, work your way through the system.

Wizard · 07-16-2011, 06:15 PM

On my EMS system its the main neutral wire that feeds through the pickup coil to read the amps.

The General · 07-16-2011, 06:37 PM

Quote:

Originally Posted by Wizard

Actually on mine and I think most Winnebagos, when the generator is running, there is no amp reading as the EMS switches over to 50amp mode.

I have a Onan Marques 5500 on my 2008 Class A Fleetwood
Bounder 35E gasser.
The EMS also switches to 50 AMP mode with no amp reading.
I can run 2 airs at the same time.

Steve

ktlyford · 07-19-2011, 01:18 AM

I also have a 2000 35U with 30 amp hookup, your not being able to read the #2 ac compressor amperage on the EMS while on generator power is how Winnebago designed the coach. On shorepower you will get valid amperage reading on the EMS. I am not positive as to why Winnebago did it this way but my guess is simplicity and cost. I have gotten very familiar with the setup as I have been dealing with putting in a 50 amp surgeguard 41260 transfer switch and yes the 30 amp Winnebagos use 50 amp switches.

The reason you are able to read the #2 compressor on shore power is that the power comes from the plug to the shore power input L1 pole of the transfer switch then to the 30 amp main breaker then to the 20 amp #2 AC breaker then to the L2 pole of the transfer switch (L2 on shorepower input) then to the #2 compressor.

The 20 amp (L2) output of the generator goes thru the transfer switch straight to the #2 compressor.

Also on the smaller Onan generators even though they have two outputs they do not put out 240 volts, the outputs are in phase cancelling each other (easily measured at the transfer switch). As the #2 out put of the generator only goes to the #2 AC the EMS only reads the L1 30 amp leg.

The wiring diagrams can be downloaded from Winnebago for verificaton.

hope this helps