Penguin II "Load Shed" wiring question

[hex_nut]

I am in the process of replacing one of the original Dometic Penguin Heat Pumps on my 2006 Monterey.  As I disconnected the wiring from the old unit, I found that the "Load Shed" (yellow wires) from the Penguin control board are connected to a 120 volt AC powered relay in the junction box.  It seems to only function to make or break continuity on the two yellow "Load Shed" wires.  I was confused by this.  My coach does not have any type of Load Shed system.  What is the purpose of this relay and does the purpose carry over to the new Penguin II that I will be installing.  I am hesitant to just hook up the two yellow wires to that relay without knowing their purpose.  Can someone out there that knows these systems better than I shed some light on things.  Thanks.

Richard   

[vito.a]

Monaco usually set up one A/C unit on the same circuit with the washer using a priority relay.  I'm guessing that's what you found.  

I hope you already know your new Penguin II A/C is not compatible with your old Dometic Comfort Control 5-button thermostat.   

Edited July 6 by vito.a

[Martinvz]

On our coach we have a load shedding ems that is next to the 120V breakers, hidden behind the metal cover plate. The power delivery is controlled at that point. 
On the Penguin2, as I recall,  there are only the 120V power connector and 2 RG58(?) telephone connectors that connects to the rear a/c and the thermostat. The load shedding is not controlled in the a/c but is part of the coach 120V power network. When I installed the Penguin2 it went in without any additional cabling for the load shedding. 
Are you possibly seeing the yellow 120V cable and thinking it is for load shedding? 
A photo or 2 may help us

[Tom Cherry]

https://newpar.newmarcorp.com/instance1Env99NEWMAR/html/images/45933P.pdf

OK….that is how the older Penguin was supposed to be wired.  Note the comments about load shedding on page 13.

NOW, to the best of my knowledge, Monaco NEVER used the Load Shed feature….as sure as I say that….at least 4 very knowledgeable and qualified members will contradict and I WILL, again, learn NEVER to trust Monaco.

As Martinvz posted….Monaco used the Intellitec EMS on many models, except the Dynasty and higher.  That system “SHED” the load via killing the AC on a circuit board.  The “shedded” items were the WD, Water Heater, Rear AC and Front AC.  These relays were for switching 20 Amp 120VAC loads.  BUT, never designed to SWITCH an inductive (motor) load like the AC’s.  Monaco knew or didn’t read or didn’t care.  Bottom line, the AC relays on these boards fail.  HOWEVER, there were also three 12 VDC (low voltage) relays.  THREE as in a MH could have 3 AC’s. The 12 VDC power to the HVAC control module was SUPPOSED to be turned ON and OFF, thus load shedding.  We have scratched our heads…but Monaco never would run the power to each through them.  Now, in all fairness, the Dometic system was designed so that only ONE of the HVAC control modules needed 12 VDC.  Then the multiplexed 2 pair data communication cable delivered 12 VDC to every other module and the Thermostat.  The simple solution….us the Load Shedding feature…I THINK…  Monaco never did…wired it AGAINST Intellitec’s instructions and folks that often overloaded on a 30 amp feed, would constantly keep switching on and off an AC. The stattup current on the inductive motor HVAC would exceed 20 amps…and as the unit wore…the compressor would pull way more.  Thus….there was a “planned” obsolescence theory….and it worked.

NOW….there will NOT be a POP QUIZ.  Wire the NEW UNIT EXACTLY LIKE THE OLD ONE. Do NOT MAKE mods, unless you are well versed and understand.

NEXT. VITO makes a good point.  If you have the 5 button thermostat, that is a CCC Multiplex system (called MPX”.  The NEW Penguin’s are a CCC2 MPX.  The NEW unit with the CCC2 module will NOT WORK.  There is a retrofit kit for the NEW CCC2 units. You have to removed the module (Dometic calls it the AC Control).  You install the CONVERSION or retrofit kit….it DOES require one or two WIRING changes to the actual HVAC unit.  All instructions are included.

SAVE the OEM CCC2 controller….and the INSTRUCTIONS.  As you add or replace more units….you will have to convert to the CCC2 MPX thermostat….and then REINSTALL and unwire or rewire the one or two “things” as outlined in the instructions.  THEN, it is, once again, a CCC2 MPX and ALL units must be CCC2.  

There is NO “upgrade” the OLD units to the CCC2.

Use the SEARCH box.  Put in CCC2, for starters, as the key word and click on EVERYWHERE….then select TOPICS….that will give you every post…

 

 

[hex_nut]

Tom

Appreciate the additional information.  I forgot to mention that the old unit was a single zone on a single 5 button thermostat.  The new Penguin II has the CCC2 control board and I will be installing the CCC2 10 button thermostat.  I am just puzzled by the strange relay in the junction box.  I cannot figure out what it could accomplish.  There must have been a reason for wiring it that way back in 2005.  Perhaps they just used standardized components in all coach assemblies regardless of whether they had a load shedding system or not.  This relay may not accomplish anything.

Richard 

[Tom Cherry]

19 hours ago, hex_nut said:

Tom

Appreciate the additional information.  I forgot to mention that the old unit was a single zone on a single 5 button thermostat.  The new Penguin II has the CCC2 control board and I will be installing the CCC2 10 button thermostat.  I am just puzzled by the strange relay in the junction box.  I cannot figure out what it could accomplish.  There must have been a reason for wiring it that way back in 2005.  Perhaps they just used standardized components in all coach assemblies regardless of whether they had a load shedding system or not.  This relay may not accomplish anything.

Richard 

I guess the question is…. Is it on your prints”.  What controls it?  Where is it connected.

We sort of flounder around when it prints for your motorhome.  Soooo…. From the top…using the install install instructions for the OEM UNIT…

What model do you have?  Then go to the link and identify the circuit diagram….based on model.

They all, to me, look very similar.  Power comes in on the RIGHT side….and goes to various points.

I tried, valiantly, to get an explanation of the Yellow wires.  Basically, if they are connected, I think, that shuts down the unit.  You can call, and we’d appreciate that, Dometic and ask them.  If making a circuit between the two yellows “kills or load sheds” then AC….then Monaco COULD have used the Intellitec EMS…but “too much trouble”.

Next up.  You say the relay is an AC powered relay???  OK, what supplies POWER to it? NOW…is it a Normally OPEN or CLOSED relay?  As in…power to it CLOSES or energizes the coil….and then….the dry contacts on the Yellow wires shut down the SYSTEM?

Can’t tell you WHAT to do…except the OLD instructions say….MAKE IT LIKE THE ONE YOU ARE REMOVING…

So, do a little sleuthing….how does the Dometic work? Find out where the AC line runs….and what powers that relay…

I’d really want to know?.  Does your manual discuss LOAD SHEDDING in the HVAC section??

get back to us….

Thanks.

 

[hex_nut]

 I have now installed the Penguin II and the CCC2 thermostat.  The unit is functioning just as I expected it to.  I have done some testing on the relay that the factory originally installed and attached the "Load Shed" wires to.  When 120 volt AC power is removed from the unit, the relay connects the 2 "Load Shed" wires together (so the relay connections for the yellow wires are normally closed).  When power is restored, the relay disconnects the 2 "Load Shed" wires (so the relay connections are now open).  This relay may have had a purpose in higher end coaches that had a load shedding system installed.  It seems to serve no purpose in my Monterey.  The only thing I can speculate is that the factory used the same junction box regardless of whether the coach had a load shedding system or not.  I am going to contact Dometic to determine if I can simply tape off the "Load Shed" wires (the yellow ones) and not connect them to anything.

Richard