Bsmt A/C 2nd compressor not coming on when running on generator

I have a 2001 Winnebago Suncruiser model 32v. The bsmt A/C is a Coleman Mach central 2 ton heat pump. The generator is an Onan 5500 watt gasoline model. All of this is controled by a Poweline Energy Mgmt System.
The AC unit operates like it is suppose to when plugged into campground electric with both compressors  being on as demand for AC is increased. However, when AC is demanded  while electricity is being generated by the onboard Onan, only one compressor goes into use. This is verified by the amps drawn as shown on the Energy Mgmt board. No amount of temperature variation or time period brings the second compressor into service. I change out the starter capacitor  on the AC's second compressor thinking it might be weak. That didn't  change anything. I loaded up the generator with other amp drawing appliances to to prove the generator could support plenty of amp draw (no problem). Thus, I ask any of you if you might have a thought or better yet a solution.
Thanks,
Wayne

Are both circuit breakers working properly on the gen?  There are 2, maybe one has tripped?

My first thought is your 20A breaker on the generator has tripped. My second thought would be that someone miswired it and put both compressors on one breaker. Your #1 compressor should be on the 30A breaker and the #2 should be on the 20A breaker so when both try to come on, it doesn't overload one breaker. Also, make sure that no other appliances are drawing current when the #2 is trying to start.

The second compressor won't run if a 30A (120v) power source is in use. My guess is the Powerline EMS is seeing your generator as a 30A source, which is sort of true. It's max output is about 45A, usually delivered as a 30A + a 20A feed. Usually there is some sort of override when the genset runs to make the second compressor available, but I don't know how that works in your particular coach.

Do you have an automatic transfer switch (genny-shore power?)

Have you tried switching the fridge and water heater to gas only, and maybe set the battery charger to a 5 amp limit?

Only the battery charger is in use when the ac goes on pulling one amp. Thanks, Wayne

I think it has a auto transfer switch as the wiring connection cover is labelled Automatic line/Generator Switch Model ATS 5070.
Breakers at gen set are both in on position.  I flipped both off  and back on with no change in 2nd compressor running.
Not sure about Electrical Management System post. The EMS was replaced. How would I know if the override is operating properly? Could you give me more info?
Thanks, Wayne
I will be checking wiring next.

Since it works fine on shore power you've ruled out anything wrong with the AC or thermostat.  I'd check the gen power flow downstream... while running on the gen and shore power disconnected, popping the cover off your ATS switch and meter if both lines L1 and L2 from the gen into the switch have power, then downstream to check if both the A/C1 and A/C2 120v circuit breakers on your panel have power.

If this all checks and you have power that far, then I'd next be thinking something might be off with how they replaced your EMS board in your circuit breaker panel. 

As far as the EMS, if you are running on gen and everything is working properly, shedding/override is disabled.  You should see the "gen" light and all of the power status lights lit, and a load displayed in the panel. 

When running the power by gen set, shore power unplugged,  L1 and L2 are powered on the load side of the ATS switch and the main panel is live. AC1 and AC2 are also live. I switched off L2 (20amp) at the gen breaker and found both AC1 and AC2 both live as is the whole main breaker panel. I switched off the L1 breaker (30 amp) at the gen set while the L2 was turned on. Nothing was live at the main panel including AC2. Thus AC1 and AC2 are operating on the 30amp side of the generator. It appears that L2 doesn't power anything. Not sure how it would be wired to run both AC lines off of the 30amp shore power and to have the two AC lines run from separate sources when in gen set mode. Both AC breakers are connected to each other by the panel making it impossible to have a separate power sources.
The EMS panel is displaying the amps in operation, the indicator  lights for other circuits and gen set light when under generator power. Any suggestions or explanations would be much appreciated!
Thanks, Wayne

Here is the model 6535 service manual, hope it is useful: https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxiaWxsbWFyaWUyMDA4fGd4OjM5YWY0OGI4N2U4N2MzODE
My #2 compressor quit running, found a severely corroded electrical connection at the compressor. Cleaned connection, #2 runs as designed.

Gary RV_Wizard said:

The second compressor won't run if a 30A (120v) power source is in use. My guess is the Powerline EMS is seeing your generator as a 30A source, which is sort of true. It's max output is about 45A, usually delivered as a 30A + a 20A feed. Usually there is some sort of override when the genset runs to make the second compressor available, but I don't know how that works in your particular coach.

Click to expand...

I have no problem running both compressors on my 2006 Journey when on 30amp power.  I have run the AC with both compressors on for many hours in 95-99 degree weather in Dallas on 30amp.  Of course I can't run the microwave or water heater with both compressors running.  The power management system knows when the generator is running so doesn't limit the compressors unless something else is on.  Such as water heater, microwave, etc.  Additionally the power management system assumes 30amp service anytime it sees single phase power.  Even if you are plugged into 15amp service. 

AStravelers said:

I have no problem running both compressors on my 2006 Journey when on 30amp power.  I have run the AC with both compressors on for many hours in 95-99 degree weather in Dallas on 30amp.  Of course I can't run the microwave or water heater with both compressors running.  The power management system knows when the generator is running so doesn't limit the compressors unless something else is on.  Such as water heater, microwave, etc.  Additionally the power management system assumes 30amp service anytime it sees single phase power.  Even if you are plugged into 15amp service.

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Odd, my Intellic system recognizes 50, 30, 20 A service; each of those lights illuminate anyway and match incoming power.

Ray said:

Odd, my Intellic system recognizes 50, 30, 20 A service; each of those lights illuminate anyway and match incoming power.

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Interesting.  My system has a button to manually select 20A, it is labeled "30/20 Amp Select".  If I pug into 20A or even 15A, the 30A light comes on.  The 20A light only comes on when the button is pressed if I am plugged into 30A, 20A or 15A. 

BTW, I know of no way the system could know if the shore power cable was plugged into 20A service rather than 30A service. 

It would be helpful if you could describe what the Intellic system sees to detect the difference between 20A & 30A shore power.

^^ mine is the same ^^

My Intellitec panel is the same as Al's also.

ASTravelers,  I have no idea how the EMS system recognizes the difference. I only know it does.

Gary RV_Wizard said:

The second compressor won't run if a 30A (120v) power source is in use. My guess is the Powerline EMS is seeing your generator as a 30A source, which is sort of true. It's max output is about 45A, usually delivered as a 30A + a 20A feed. Usually there is some sort of override when the genset runs to make the second compressor available, but I don't know how that works in your particular coach.

Click to expand...

I know this is an old post, however I  must tell you my basement heat pump DOES run both compressors on a 30A feed to the MH. When both compressors are running the draw is 23-24A. I have done it many times over the years.
If I turn another big load the EMS drops #2 compressor to prevent tripping the breaker.
Perhaps the service manual will  be useful:  https://www.airxcel.com/DesktopModules/RvProduct/Pdf/1976281.pdf

Ray said:

My #2 compressor quit running, found a severely corroded electrical connection at the compressor. Cleaned connection, #2 runs as designed.

Click to expand...

Ray,

Alright Brother... Hoo-AH!

He Applied the KISS principle. Keeping it Simple Silly. 

Looked in his Army/Problem Solving Tool Bag and went with the old "Eye Ball" Method of Repair.

I am with you. ) ) 

You have to look at the battle field before you can develop a course of action and implement your plan. 

I also remember my 8 steps to problem solving Army Teachings, 1SG!

Brain Storming here at RV Forum we find out a owners of Brand "X" Travel Trailer for eXample: They all inherently pool with moisture or some crazy quirk all model "X" model have. 

Something you would not know unless you are connected to another actual owner of the same model.

Some other stories we we read about here on the forum you have to get out your popcorn for as you read with one eye shut due to the horror or the narrowly averted Disaster, it is like some of that very same eXact model "X" that people rant and rave about how they Love others or few tell stories how theirs has totally failed, right out the MFG's Gate on the way the Forest / Adventure. 

Like it was a Lemon or it was like "Proto/eXperimental Type Stuff where Model "X" Brand New Gear Falls apart on the Launch Pad and can't be repaired without almost total destruction.

...I present the Boat-Addict horror show as proof of truth to my words I speak here.

He unnnn fortunately hit the Beer Thirty Lotto of Rolling Snake Eyes at the Craps Table and rolled a hidden Disaster off the Assembly Line.  This guy is a Master Boat Builder and could not solve the Repair Puzzle.

I love my Winnebago, but I trust her about as far as I can throw her. 

These things have to be constantly tinkered with it seems. 

RV Forum is Powerful stuff for RVrs.

Hoo-AH!  Atta Boy Ray.  )

Got a bit off topic and long winded, but I find this an interesting thread.  I have heard this 2 compressor set up in the basement is a thing of the past.  I am sure more so of a slow down on the Assembly line more so than a Bad Design.  Sure it boils down to cutting into the bottom line Profit why the design was NiXed. 

I bet this Model looks "sleek" as a big box can that is viewing it from a profile view.  I am going to have to start looking for your model when I see RVs out on the Open roads.

This Guy performed a DIY AC Install on his and killed his sleek look but I can see he solved a heat problem...I guess this is a direct wire to the camp pedestal separate circuit.  See attached..

https://d3qrmewc1af01c.cloudfront.net/lazydays.com/16687119-af35-47d1-b3f6-8947b034c91b.jpg

JD

Ray said:

ASTravelers,  I have no idea how the EMS system recognizes the difference. I only know it does.

Click to expand...

Since there is absolutely NO difference in the electrical makeup between 30amp service, 20amp service and 15amp service the EMS has no way to recognize the difference.  That is why there is a push button on the EMS to allow the operator to tell the EMS the RV is plugged in to 20amp service.

30amp, 20amp and 15amp service all have the same 3 wires, a hot wire, a neutral wire and a ground wire. All the EMS can see is these 3 wires and has no way to detect any difference between the 3 services. 

While there will be a difference in the circuit breakers (30, 20, or 15) the only  time they would come into play is if the amps the RV is pulling exceed the current rating of the C/B.  Then the C/B will trip dropping the power to the RV.   

I suggest that at some time you test your system again to verify its operation by pugging into 30amp and then into 20 or 15 amp outlets.

P.S.  I just pugged my 2006 Journey into a 15amp outlet and the EMS turned on the 30amp light. 

Absolutely correct Al.