Smart EMS controller

[CLIFF918]

On 50 amp shore power had both ACs running everything was working fine and while I was outdoors, the air conditioners shut down and I thought they had reached the proper temperature but the wife said there was no display on the thermostat and troubleshooting everything points to this EMS controller that’s in the back of the coach anybody have any Dealings with the EMS controller 2002 Monaco diplomat.

Also my electric portion of the hot water heater has not worked for I would say a month or so but that didn’t bother us cause we usually use gas anyway, but that is also controlled by that EMS controller so I’m thinking that that board has done left us out to dry  comments ?

 

[Tom Cherry]

1 hour ago, CLIFF918 said:

On 50 amp shore power had both ACs running everything was working fine and while I was outdoors, the air conditioners shut down and I thought they had reached the proper temperature but the wife said there was no display on the thermostat and troubleshooting everything points to this EMS controller that’s in the back of the coach anybody have any Dealings with the EMS controller 2002 Monaco diplomat.

Also my electric portion of the hot water heater has not worked for I would say a month or so but that didn’t bother us cause we usually use gas anyway, but that is also controlled by that EMS controller so I’m thinking that that board has done left us out to dry  comments ?

 

ONE at a time.  Lets deal with HVAC. NO….the Intellitec EMS does NOT control the thermostats.  Here is how the EMS works….and then we’ll deal with the HVAC. The EMS is a LOAD SHEDDING device.  IF you are on 50 AMP power….it does NOTHING NADA.  WHY?  You have the max power that the MH needs.  Now on your Genny, it will diplay the total AMPS USED.  Your Genny may have a DUAL POLE 30 or 35 A circuit breaker on it.  So the max amps you will get is the total….70 or 30 (2 TIMES the rating of the breaker.  BE AWARD….KEENLY AWARE.  Never overload the generator.  The #6 Wiring is only good for 55 AMPS.  Go above that….TROUBLE and you do NOT want to do that.  
 

If you are on 30 AMP power….that is ONLY ONE Line or LEG.  Therefore, the EMS will SHED or start cutting off when the load exceeds 30 A. If you are on a 20A receptacle…..there is a BUTTON to push (toggles) and you need to select 20 A, otherwise you will overload and possible melt the 20A cord or worse….catch it on FIRE.  READ THE MANUAL…. Section 8.  VERY IMPORTANT.

Now…your problem is one of TWO things.  ONE….you have a blown FUSE in the HOUSE Distribution panel.  Again….read the manual and locate it.  THERE is NO FUSE MARKED HVAC….fuss at Monaco.  Test or replace every fuse….most likely a 10 or 15 amp fuse.  Mine is marked SATELLITE….  

That sounds like the problem.  That fuse has two lines or a line that runs to each of the Control Modules in each HVAC unit.  The 15KW are accessible by pulling off the outside cover.  The 13.5KW may be accessible from inside after you remove the white filter conver.

There have been several recent discussions on this.  Search and read.  If the fuse is blown….no power.  The Thermostat does NOT have 12 VDC run to it.  There is a 4 wire Data communications cable…..it is DIFFERENT from a PHONE cable as the colors or wiring order is different.  TWO of these wire supply POWER or 12 VDC.  That is what runs the Thermostat.  Here is the layout.  Thermostat has a cable to the front.  There are TWO inline connectors.  There are TWO lines dangling down or coming from the roof.  They connect to the control module on the roof.  The 12 VDC is then sent back to the thermostat.  The other two wires are a multiplexed line.  Look that up.  It sends coded digital signals from the thermostat to each unit.  So…thermostat to front…up and back down to the plenum.

There is ANOTHER data cable that runs to the rear AC.  Odds are….only ONE inline connector or one data cable back there.  
 

ASSUMING the fuse…..then….you have to do a complete system reset.  TURN OFF the power switch on the bottom.  HOLD IN the top (mode) and bottom (zone) buttons….while they are pushed in….turn ON the thermostat.  FF should appear.   If this fails……then…

GO to the front HVAC.  Remove the cover.  Use alcohol and a Q-Tip or CONTACT Cleaner (NOT….NEVER ELECTRICAL…it melts the plastic.  Clean the contacts of the Male and Female ends.  Then plug in…push firmly… Unplug…do that a few times.  All FOUR contacts must mate and have a circuit.  Plug and unplug will clean them.

NOW…do BOTH connectors…or if the cables run up and to the roof….clean the ends up there.  Do the rear also,

NOW REPEAT the reset.  If you lose power to the control modules….as in a fuse or if there is a bad connection….you have to reset and let the thermostat figure out what control modules are there. (The thermostat will control up to 4 zones).  It also has to “chat” with each control module.  That’s it.

LACK of power is usually a fuse.  It CAN be the first connection in the front.  Lack of a zone…as in you only have zone 1 or zone 2 is a connextion issue,

FINALLy…. NEVER USE THE BOTTOM ON/OFF switch except for RESET.  It BREAKS.  Dometic quit making them and the aftermarket replacement is expensive.  Toggle through MODE….to OFF….then MODE for Zone 2.

[CorinthWest]

Last week, my EMS caught fire.  I'm in the process of replacing the control board.  Apparently, Intellitec used underrated relays for controlling appliances (particularly A/C units).  It was the relay for the forward A/C unit that caused the fire.  It wasn't bad, but I still have a lot of cleanup work to do.  I have the new board, and it cost ~$300.  Easy enough to replace.  In the meantime, I have taken a suggestion from another member to simply wire nut the circuit breaker wire directly to the A/C wire and bypass the EMS altogether.

Do a little research, this is a comon problem.  However, I will say that the EMS DOES NOT control or supply any 12V power - only 110V, and your thermostat is powered by 12V.  I'm not sure why your thermostat went dead.  Perhaps the issue isn't in your EMS?  You can check it with a voltmeter.

FWIW:  When I found the fire, the breaker panel cover was red hot, but not hot enough to blister the paint.  There was virtualy NO INDICATION there was a fire behind the panel cover.  Just a smell, and a LOT of heat.  Fortunately, the fire was contained in the breaker box.  But I learned that if your breaker panel cover is hot to the touch, you probably have a problem with the EMS board and this presents a HUGE fire hazard.

Geez, between the 1200LR, the EMS, 30 gallons of liquid propane, and 100 gallons of gasoline, all moving down the highway at 65 MPH, perhaps we should have our brains examined?  Bombs on wheelz.....

[Tom Cherry]

2 minutes ago, CorinthWest said:

Last week, my EMS caught fire.  I'm in the process of replacing the control board.  Apparently, Intellitec used underrated relays for controlling appliances (particularly A/C units).  It was the relay for the forward A/C unit that caused the fire.  It wasn't bad, but I still have a lot of cleanup work to do.  I have the new board, and it cost ~$300.  Easy enough to replace.  In the meantime, I have taken a suggestion from another member to simply wire nut the circuit breaker wire directly to the A/C wire and bypass the EMS altogether.

Do a little research, this is a comon problem.  However, I will say that the EMS DOES NOT control or supply any 12V power - only 110V, and your thermostat is powered by 12V.  I'm not sure why your thermostat went dead.  Perhaps the issue isn't in your EMS?  You can check it with a voltmeter.

FWIW:  When I found the fire, the breaker panel cover was red hot, but not hot enough to blister the paint.  There was virtualy NO INDICATION there was a fire behind the panel cover.  Just a smell, and a LOT of heat.  Fortunately, the fire was contained in the breaker box.  But I learned that if your breaker panel cover is hot to the touch, you probably have a problem with the EMS board and this presents a HUGE fire hazard.

Geez, between the 1200LR, the EMS, 30 gallons of liquid propane, and 100 gallons of gasoline, all moving down the highway at 65 MPH, perhaps we should have our brains examined?  Bombs on wheelz.....

Technically….MONACO caused your fire.  There are THREE relays designed to control the HVAC units.  The design….and INTELLITEC’s instructions…..turn On or Off the HVAC by switching the THERMOSTAT power.  OPPS.  We have a MPX controlled system.  If you kill the 12 VDC, you kill every AC…and maybe have to reset the thermostat.

YES…the OP’s issue is NOT the EMS.

Now….there are 4 AC relays for switching normal, NON INDUCTIVE loads.  A water heater is NON INDUCTIVE.  Every HVAC has a starting capacitor.  It provides a VOLTAGE boost.  The Blower and the Compressor have MOTORS.  So there is a surge or SPIKE in the starting AMPS.  New, maybe the capacitor would work…but when the HVAC gets older….the HIGHER or larger the spike.  The HVAC runs around 15 - 17 Amps.  The starting current may be in the mid 20’s….just a brief…almost impossible to be seen spike,,,,and it will not, ordinarily, kick off a breaker.  But…when you push the HVAC and don’t understand that every time you are on 30 amps….it is dadgummed near impossible yo keep the AC’s running….and they shed OFF, then back on….the contacts in those relays FAIL.  They were NEVER rated for an inductive load.  SO MONACO….GOOFED….it was pointed out at every rally, I was told…

OK….new board…..here is what I WOULD DO.  Find a 25 AMP….FLA relay….it needs to be rated for an INDUCTIVE load.  12 VDC coil.  So….you put the HVAC’s on the HVAC relays.  You have to follow the instructions and reconfigure the shed sequence and assign HVAC 1 and HVAC 2….off the THREE low voltage sets of contacts.  SO….when the HVAC 1 relay is energized….12 VDC goes to the coil.  That energizes the coil.  The 25 A contacts are closed. Then….when the EMS sheds….it kills the relay…thus the contacts.  

That is the ONLY way to properly install the EMS on a Dometic MPX thermostat system.  It has taken me years to resolve this…..with some input from others and noodling this out….write it up….otherwise….they will blow again.  The OLDER the HVAC….the quicker they will burn up the NEW relay…

Lucky no fire damage….relatively speaking….

[Patricia Ferrara]

2 hours ago, CLIFF918 said:

On 50 amp shore power had both ACs running everything was working fine and while I was outdoors, the air conditioners shut down and I thought they had reached the proper temperature but the wife said there was no display on the thermostat and troubleshooting everything points to this EMS controller that’s in the back of the coach anybody have any Dealings with the EMS controller 2002 Monaco diplomat.

Also my electric portion of the hot water heater has not worked for I would say a month or so but that didn’t bother us cause we usually use gas anyway, but that is also controlled by that EMS controller so I’m thinking that that board has done left us out to dry  comments ?

 

We had both ACs shut down this morning also. As Tom Cherry pointed out, the reset procedure is where we started. We had an E1 error code, so on a post back in February, Tom suggested locating a phone cord connector, which was accessed in our rig inside, by pulling the filter from the front AC. Tom suggested rubbing alcohol & Q-tips to clean the male & female connectors; ours was quite dirty (see pic). Be careful that there’s no cotton from the Q-tip tangled up in the female connector - I had to use some tweezers to pull out a bit that got stuck.

(And I forgot to mention that there was NO POWER running to the AC’s, even 12 volt. Don’t like to take any chances on getting zapped).

Cleaning the phone cord connectors and rebooting the thermostat did the trick. Hope that your issue is resolved as easily!

[CLIFF918]

Thanks for all the input. I’m not in the position right now to tear into it. I am in a park in South Carolina, but will be returning to Florida in on Monday and I will get after it then that idea of tying directly to the breaker sounds like it might work. I may try that before we leave here so we get some AC back into the coach. Thanks again for the input. I’ll let you know what happens. 

[CLIFF918]

OK, thanks all for the input. My problem is not that the connectors or anything like that need to be cleaned. I just went in and decided to look at how I would wire that AC unit unit number one to AC so I could bypass it. In doing so I tapped or happened to hit the control board with the blunt end of the screwdriver and lo and behold the thermostat display came on on the thermostat for whatever known reason. I turned the AC on and it ran for about five minutes and then everything went dead again I’m convinced that that EMS control board is bad or at least one of the relays on it is bad and they’re not replaceable so off to the Internet, I will go and see if I can order a board . Unfortunately they do not tell you what goes on inside that board. I am an old school technician and very familiar with troubleshooting to the component level however, we need to know what goes on inside there.

[Tom Cherry]

1 minute ago, CLIFF918 said:

OK, thanks all for the input. My problem is not that the connectors or anything like that need to be cleaned. I just went in and decided to look at how I would wire that AC unit unit number one to AC so I could bypass it. In doing so I tapped or happened to hit the control board with the blunt end of the screwdriver and lo and behold the thermostat display came on on the thermostat for whatever known reason. I turned the AC on and it ran for about five minutes and then everything went dead again I’m convinced that that EMS control board is bad or at least one of the relays on it is bad and they’re not replaceable so off to the Internet, I will go and see if I can order a board . Unfortunately they do not tell you what goes on inside that board. I am an old school technician and very familiar with troubleshooting to the component level however, we need to know what goes on inside there.

Ok….in response to your comments…as well as education.  Here is more info…

Technically, you ONLY need 12 VDC to ONE controller.  THEN the Data Com Cable will send it BOTH ways.  Monaco did a bit of OVERKILL.  They ran (or were supposed to….never doubt the creativity of the untrained assemblers).  SO if even ONE of the controllers has POWER….then the cable will take it to EACH END of the. Data buss or run.

From what you just told us, the RJ11 female connectors on the control module are DIRTY.  SOMETIMES Monaco us the short extensions.  Scroll back up to Pat’s post.  These are nothing but Data Com Extension Cables.  There are TWO female RJ11 connections on the control module.  There is NO POLARITY.  So, the thermostat can be plugged into either one.  The data and power signal goes either way.  You lucked into bumping the loose connection.

I can assure you…..that you will have another outage and it will be on the hottest day.  I lost my rear AC on the way from Myrtle Beach to Charleston (River Oaks).  It took some cleaning and I got it back,  NOW….FWIW.  Since the connection was broken….then the poor thermostat don’t know who or what is out there.

ANYTIME you lose power (fuse or bad connection), then you MUST do the reset.

The other thing……running a “line” would NOT have fixed it.  You need to understand the system and have a VoltMeter and learn HOW to trouble shoot.  

You also need to learn to search….sort of like going to the library.  I knew there was a similar topic going.  Helped out that member.  I used Dimetic Controller Dynasty.  Here is a link to that topic.  Lots of great info.

SPECIFICALLY he took a great picture.  I just did a screen shot.  All you would have had to do….measure the voltage on the two items he circled.  BTW, we DO think that Monaco might have goofed or the 12 VDC going to his rear AC, seems to be missing.  BUT, he has OTHER issues….He has “LOST” a zone.  He had it before….did some 120VAC work…..no ZONE 3.  Odds are….he BUMPED on of the RJ11 and that took out ZONE 3…but, his other zones worked,

That is the beauty of our search…

It is ALSO the reason that we only permit ONE ISSUE per topic.  I am like you….I often teach.  I explained WHY it was NOT the EMS.

Therefore, please do not go back and start asking questions about your WATER HEATER….and the possibility of a BAD EMS. You need to get out your volt meter  and  start to check for incoming AC.  It could ALSO be a faulty switch the one for selecting GAS v Electric.

Look at your prints.  Start to troubleshoot.  One of the biggest obstacles that the staff and our great bunch of contributors is….HAVE FACTS.  TROUBLESHOOT.  At least 50% of the time when a member has developed a preconceived “cause”….it is wrong.  

Good luck….just remember that your entire HVAC plugs and connectors have “failed”.  Lot easier to fix NOW than when wife and family are sweltering and you are frustrated….take that to the bank.  The members that do preventive maintenance have MORE time to enjoy and their blood pressure stays normal.

 

 

[Tom Cherry]

1 hour ago, CLIFF918 said:

OK, thanks all for the input. My problem is not that the connectors or anything like that need to be cleaned. I just went in and decided to look at how I would wire that AC unit unit number one to AC so I could bypass it. In doing so I tapped or happened to hit the control board with the blunt end of the screwdriver and lo and behold the thermostat display came on on the thermostat for whatever known reason. I turned the AC on and it ran for about five minutes and then everything went dead again I’m convinced that that EMS control board is bad or at least one of the relays on it is bad and they’re not replaceable so off to the Internet, I will go and see if I can order a board . Unfortunately they do not tell you what goes on inside that board. I am an old school technician and very familiar with troubleshooting to the component level however, we need to know what goes on inside there.

Just reread….did your do the reset?  This may NOT be like any system that you are familiar with.  Clean the contacts and connectors.  Reset the thermostat.  If it dies again….go up and measure for 120 VAC voltage.  These are the correct steps.  If you have NO VOLTAGE, then do the following.

MAKE SURE every breaker is ON!  Folks shoot themselves in the foot.  The EMS is picky.  OK…NO JOY….STOP.  Remove the panel's cover..  I’d turn OFF the power (AC). NOW the printed circuit board in the lower right is the EMS.  There is a 3 amp fuse hidden behind a harness.  Unplug all harnesses.  Remove the fuse.  Wait 5 minutes.  Reinstall the harnesses.  Put in the fuse.  This resets it.  YES….there is a BUNCH of complex and unfamiliar electronics here.  We have PROS that learn.

NO JOY.  Then…with POWER OFF.  Use your “eyes” or continuity scale.  Trace the Front AC breaker circuit.  BTW….the breakers vibrate loose.  Heat up….trip. ASSUME no tripped breakers.  OK….the AC FRONT breaker will go to the front HVAC EMS terminal (download the manual).  Then find the OUTPUT for the Front AC.  Disconnect both blacks.  Wire nut then.  NOW the front will not shed….WAY EASIER than trying to jimmy or hack the wiring.

Based on your tech background…..this is HOW you troubleshoot.  If the AC keeps stopping….ain’t NO FAULT of the EMS.  
NOW…I aIn’t gonna bet on WHERE the issue…but after you do the proper troubleshooting….you will know….many folks throw dollars for new components and replacement boards….then lament that they didn’t understand or didn’t troubleshoot.

That’s how the techs do it….good luck

[Tom Cherry]

FWIW…I have helped and troubleshot, literally, over a hundred of these in the past 15 years.  90% of the time….bad data com connection.  Then the control module…finally a thermostat. Once it shuts down again, verify incoming 120 VAC.  The Front AC is the LAST one shed…so, no voltage….maybe the EMS. But, if voltage (120 VAC) then after doing the simple things….cleaning connextions.  Then pull the rear control unit.  Take a picture of each one’s DIP switches.  Reprogram the rear for the front.  Install.  Do the reset….then test.

 

[Rikadoo]

Before i finally replaced my transfere switch my yealy maintance routine was to go thru an tighten / torque all my screws that secure the wires, i was amazed how loose they had been, on one of those occasions i decided to pull the cover over the breakers an check those. Almost every one had no torque to them an a few were quite loose, on back of the cover lower right is the spec. I used my square bit with a adapter an used my inch pould torque wrench. Loose connections will create a lot of heat, just remember if you choose to do this UNPLUG your RV an TURN THE GENERATOR OFF.

[Rick Chambers]

19 hours ago, CorinthWest said:

Last week, my EMS caught fire.  I'm in the process of replacing the control board.  Apparently, Intellitec used underrated relays for controlling appliances (particularly A/C units).  It was the relay for the forward A/C unit that caused the fire.  It wasn't bad, but I still have a lot of cleanup work to do.  I have the new board, and it cost ~$300.  Easy enough to replace.  In the meantime, I have taken a suggestion from another member to simply wire nut the circuit breaker wire directly to the A/C wire and bypass the EMS altogether.

Do a little research, this is a comon problem.  However, I will say that the EMS DOES NOT control or supply any 12V power - only 110V, and your thermostat is powered by 12V.  I'm not sure why your thermostat went dead.  Perhaps the issue isn't in your EMS?  You can check it with a voltmeter.

FWIW:  When I found the fire, the breaker panel cover was red hot, but not hot enough to blister the paint.  There was virtualy NO INDICATION there was a fire behind the panel cover.  Just a smell, and a LOT of heat.  Fortunately, the fire was contained in the breaker box.  But I learned that if your breaker panel cover is hot to the touch, you probably have a problem with the EMS board and this presents a HUGE fire hazard.

Geez, between the 1200LR, the EMS, 30 gallons of liquid propane, and 100 gallons of gasoline, all moving down the highway at 65 MPH, perhaps we should have our brains examined?  Bombs on wheelz.....

 

I second this!  A relay on my Intellitec board failed.  The one that controls my front A/C. My electrical engineer brother in law figured out a work around while we are on the road in Alaska.  We have not needed the A/C much up here but his bypass has worked great!  I will be ordering a new board when we get home in a few weeks.

[cbr046]

26 minutes ago, Rick Chambers said:

I will be ordering a new board when we get home in a few weeks.

Why not replace the relay (or pc board traces) on the board?  Better yet, get your EE brother in law to do it 😄

- bob

[jacwjames]

In 2014 I had my coach plugged into my house.  In the middle of the night we had one heck of a storm roll through and lighting hit the pole that the transformer was on that fed the house.  Blew the lightening arrestor off the pole.  We had one TV in the house that got hit and later when I was getting ready to leave on a trip found that the EMS load display wasn't working. 

Contacted M&M Electronics and they walked me through the reset procedure but ultimately determined the board was bad.  I ordered a new board from M&M and had it shipped to our location.  To get by I bypassed the EMS board for one AC until I could receive and install the new board. 

My 750 board was obsolete so I had to upgrade to the newer 760 board which required a new load center and wiring harness.  Once I figured out how to wire it in it wasn't too bad of an install, the instructions kinda sucked. 

[CLIFF918]

Yesterday the front air conditioner came on all by itself without me doing anything to it all day long the thermostat display was completely dead and I just left it as it was and we can troubleshoot it go back to Florida however, it quit again this afternoon about 3 o’clock this afternoon it stopped so I took advantage of that and went and cleaned all of the data connections all of the Connectors that Tom mentioned to make sure they were clean and I came back with three or four clean Q-tips so those connectors were pretty clean. They were nice and shiny but everything back together and lo and behold. It started up again and it is running right now, so I don’t have a load display on it from the EMS so I gotta believe that that is got some issues inside it and I’ve ordered a new one.

I also did the reset on the EMS and the reset on the thermostat didn’t seem to change anything but front area. AC is running right now. I’ll see how long it last..

 

[Tom Cherry]

54 minutes ago, CLIFF918 said:

Yesterday the front air conditioner came on all by itself without me doing anything to it all day long the thermostat display was completely dead and I just left it as it was and we can troubleshoot it go back to Florida however, it quit again this afternoon about 3 o’clock this afternoon it stopped so I took advantage of that and went and cleaned all of the data connections all of the Connectors that Tom mentioned to make sure they were clean and I came back with three or four clean Q-tips so those connectors were pretty clean. They were nice and shiny but everything back together and lo and behold. It started up again and it is running right now, so I don’t have a load display on it from the EMS so I gotta believe that that is got some issues inside it and I’ve ordered a new one.

I also did the reset on the EMS and the reset on the thermostat didn’t seem to change anything but front area. AC is running right now. I’ll see how long it last..

 

WHOA.  What POWER are you ON?  If you are on 50 AMP, then the EMS is LOCKED OUT or BYPASSED.  It  had TWO terminals....  They are fed by Line 1 and Line 2.  IF the power is 220V 50 A....then you will have 220 VAC on the terminals.  Therefor the EMS says... HEY....they have 50 AMPS.  Ain't nothing that I GONNA DO.  It is BLANK. Which is CORRECT and NORMAL. It is NOT an AMMETER that measures any line.  It only measures the NETURAL.  From your tech experience, I assume you know that on a 220 VAC circuit....the Neutral is swapping 120 times (2 times the half sine wave cycle) and the NEUTRAL only carries the Algebraic sum of the current.  THUS, a balanced load or 15 amps on Line 1 and Line 2 will READ ZERO if you use an ammeter.  The EMS only measures and displays CURRENT when the system is "TOLD" by the panel....we ain't GOT no 220 VAC .

The EMS ONLY sheds when you are on a SINGLE line (or actually, on your Genny.  BUT, your Genny is NOT a 220 VAC so when the J1 and J2 (memory) or the Line 1 and Line2 measures....they do NOT get 220 VAC.  They get zero.  THEN, the EMS says.  HEY NO 50 AMP 220 Vac.  GOTTA GO TO WORK.

That's HOW it WORKS.  If your Thermostat is working....GOOD Data Buss for the MPX.  If the AC is running and you are ON 50 AMP....the EMS is on Standby.  Wanna TEST.  Kill your SHORE.  Then start the Genny.  Let it warm up for 5 minutes.  BTW....TURN OFF ALL AC using the MODE.  NOW.   Turn Zone 1 on.....ODDS are.....whatever Amps you were seeing....will then jump by 15 - 17 Amps.

THEN you KNOW the EMS is working.

Hope this makes sense.  Your description ...WITHOUT tell us the PEDESTAL POWER is hard to follow...but I think you will see.  Read the EMS manual...

Here is a copy...  It is pretty clear in the front....and all the circuits are there....

 

Intellitec EMS System 5300684.000.pdf

[Rick Chambers]

23 hours ago, cbr046 said:

Why not replace the relay (or pc board traces) on the board?  Better yet, get your EE brother in law to do it 😄

- bob

He said he might be able to replace the relay, he said he wants to look at it.  However, I am thinking I might just replace the whole board since one has failed, others will probably follow at the most inconvenient time.

[Tom Cherry]

Without any feedback and the elementary troubleshooting requested….??  Simple thing such as IS THERE 120 VAC input COMING INTO the Front HVAC J-Box.  This is a guessing game and the “usual suspect” is the EMS. 

In addition, it appears, from the posts, that there was NO RESET…as required, performed on either occasions.  This is mandatory. A “corrupted” power ON to the thermostat WITHOUT a reset has been known to have all sorts of UNEXPLAINED events….and another zone can “get involved.  That’s why Dometic flatly and plainly states thaf you MUST preform the reaet after any cleaning or unplugging or power interruptions

The Point…it is FUTILE to “guess” and then order a new board…until the EMS has been tested. That has been posted, repeatedly, and requested.  As well as the simple steps and order….

YES. Members HAVE supposedly pulled the relay and replaced it.  Members have bypassed the Front relay.  If the relay is the only issue, then the EMS will quickly shed the 2nd and 3rd tiers.  The front AC is the last to go. The common mistake….GOTTA RUN TWO AC’s on 30Amp….even on Genny, folks overload the neutral and damage things,

Until there is hard data and proper troubleshooting and feedback….this topic is basically “DEAD IN THE WATER”. Totally guesswork!

Ordering and installing a new board with nothing but a HUNCH and some tripe internet garbage ….MIGHT work….but we have been down this path before  on this and many other issues….NEW hardware and not finding the real source doesn’t work,

BUT, our charter is to provide help and also assist and provide the correct troubleshooting techniques…and we have many members that do such…..

We need feedback.